From Newsgroup: uk.d-i-y

We've recently found out that in the very near future with any marine
surge flood about 0.1m higher than the one in 2024, SSEN would
pre-emptively remotely cut the local electricity supply to protect their lowest local substation transformer. So the 30 or so subfloor
residential sump pumps will stop when most needed.
So perhaps buy a few petrol driven pumps, but the problem there its
unlikely they would be maintained and would lie idle in sheds for 5
years say, and not run when required.
So how high a capacity/throughput/amperage of pumps using 12volt (from
car batteries) and where can they be obtained eg for large garden
water features perhaps, ie bigger than windscreen washer pumps say.
Or even perhaps human powered pumps capable of lifting one metre , efficiently by perhaps 2 people, an action like those "wild west"
railway human powered personel carriers, or old sailing ship human
powered bilge pumps, and where to obtain such.
An easy job to extend vertically the sumps, as all the same make and
size, just remove the covers and bolt on a small vertical extender ,
for access for such supplemental pump piping.
--
Global sea level rise to 2100 from curve-fitted existing altimetry data <http://diverse.4mg.com/slr.htm>
--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: uk.d-i-y

We've recently found out that in the very near future with any marine
surge flood about 0.1m higher than the one in 2024, SSEN would
pre-emptively remotely cut the local electricity supply to protect their lowest local substation transformer. So the 30 or so subfloor
residential sump pumps will stop when most needed.
So perhaps buy a few petrol driven pumps, but the problem there its
unlikely they would be maintained and would lie idle in sheds for 5
years say, and not run when required.
So how high a capacity/throughput/amperage of pumps using 12volt (from
car batteries) and where can they be obtained eg for large garden
water features perhaps, ie bigger than windscreen washer pumps say.
Or even perhaps human powered pumps capable of lifting one metre , efficiently by perhaps 2 people, an action like those "wild west"
railway human powered personel carriers, or old sailing ship human
powered bilge pumps, and where to obtain such.
An easy job to extend vertically the sumps, as all the same make and
size, just remove the covers and bolt on a small vertical extender ,
for access for such supplemental pump piping.
--
Global sea level rise to 2100 from curve-fitted existing altimetry data <http://diverse.4mg.com/slr.htm>
--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: uk.d-i-y

N_Cook wrote:

We've recently found out that in the very near future with any marine
surge flood about 0.1m higher than the one in 2024, SSEN would pre- emptively remotely cut the local electricity supply to protect their
lowest local substation transformer. So the 30 or so subfloor
residential sump pumps will stop when most needed.
So perhaps buy a few petrol driven pumps, but the problem there its
unlikely they would be maintained and would lie idle in sheds for 5
years say, and not run when required.
So how high a capacity/throughput/amperage of pumps using 12volt (from
car batteries) and-a where can they be obtained eg for-a large garden
water features perhaps, ie bigger than windscreen washer pumps say.
Or even perhaps-a human powered pumps capable of lifting one metre , efficiently by perhaps 2 people, an action like those "wild west"
railway human powered personel carriers, or old sailing ship human
powered bilge pumps, and where to obtain such.
An easy job to extend vertically the sumps, as all the same make and
size, just-a remove the covers and bolt on a small vertical extender ,
for-a access for such supplemental pump piping.

I'd have thought that car batteries (and humans) wouldn't be very well
suited for coping with the duration of a "marine surge".

Where are you going to pump it to?

I'd look for a second hand trash pump or similar and suitable lengths of suction hose ...

--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: uk.d-i-y

On 12/01/2026 16:57, Andy Burns wrote:

N_Cook wrote:

We've recently found out that in the very near future with any marine
surge flood about 0.1m higher than the one in 2024, SSEN would pre-
emptively remotely cut the local electricity supply to protect their
lowest local substation transformer. So the 30 or so subfloor
residential sump pumps will stop when most needed.
So perhaps buy a few petrol driven pumps, but the problem there its
unlikely they would be maintained and would lie idle in sheds for 5
years say, and not run when required.
So how high a capacity/throughput/amperage of pumps using 12volt (from
car batteries) and where can they be obtained eg for large garden
water features perhaps, ie bigger than windscreen washer pumps say.
Or even perhaps human powered pumps capable of lifting one metre ,
efficiently by perhaps 2 people, an action like those "wild west"
railway human powered personel carriers, or old sailing ship human
powered bilge pumps, and where to obtain such.
An easy job to extend vertically the sumps, as all the same make and
size, just remove the covers and bolt on a small vertical extender ,
for access for such supplemental pump piping.

I'd have thought that car batteries (and humans) wouldn't be very well
suited for coping with the duration of a "marine surge".

Where are you going to pump it to?

I'd look for a second hand trash pump or similar and suitable lengths of suction hose ...

The exsting "solids" pumps are 1KW rating, so far I've only come across
110 or 240V sewage/trash pumps and 12V "clean" water pumps of low
amperage. Hopefully there are 12V trash pumps of at least 20 amps
rating available somewhere, for boats or caravans perhaps. Even a
quarter the power is better than nothing. Luckily the peak of marine
surges would be less than an hour even for the lowest house, unlike rainfall/non-tidal river flooding situations which can peak for days.

Pumping to the general floodwater outside the house , like the fitted
pump outlets
--
Global sea level rise to 2100 from curve-fitted existing altimetry data <http://diverse.4mg.com/slr.htm>
--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: uk.d-i-y

N_Cook <diverse@tcp.co.uk> wrote:

We've recently found out that in the very near future with any marine
surge flood about 0.1m higher than the one in 2024, SSEN would
pre-emptively remotely cut the local electricity supply to protect their lowest local substation transformer. So the 30 or so subfloor
residential sump pumps will stop when most needed.
So perhaps buy a few petrol driven pumps, but the problem there its
unlikely they would be maintained and would lie idle in sheds for 5
years say, and not run when required.
So how high a capacity/throughput/amperage of pumps using 12volt (from
car batteries) and where can they be obtained eg for large garden
water features perhaps, ie bigger than windscreen washer pumps say.
Or even perhaps human powered pumps capable of lifting one metre , efficiently by perhaps 2 people, an action like those "wild west"
railway human powered personel carriers, or old sailing ship human
powered bilge pumps, and where to obtain such.
An easy job to extend vertically the sumps, as all the same make and
size, just remove the covers and bolt on a small vertical extender ,
for access for such supplemental pump piping.

Pumps can be a sod to prime just when you need them unless they are submersibles and cellars are often full of debris which can make things
harder . An electric submersible of the right sort can usually handle
debris of a certain size and can be hauled up on a rope to clear it if it does get blocked. So pop up the road to Machine Mart and get a suitable
pump to run it and a generator to provide the power, best placed outside especially if petrol ,generators would have more tasks and easier to run occasionally, plus as well as the pump you could run a light if it has
enough output.
. More expensive would be a pneumatic diaphragm pump which can also handle mucky water , you would need an engine driven compressor to run it . Pity Belsize boatyard has gone , they would have had plenty of pumps but if 12V
is what you want a bilge pump may be the answer but one with a decent flow
rate is going to need a fair number of amps ,car batteries wonrCOt last long.

GH
--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: uk.d-i-y

On Mon, 1/12/2026 2:03 PM, N_Cook wrote:

On 12/01/2026 16:57, Andy Burns wrote:

N_Cook wrote:

We've recently found out that in the very near future with any marine
surge flood about 0.1m higher than the one in 2024, SSEN would pre-
emptively remotely cut the local electricity supply to protect their
lowest local substation transformer. So the 30 or so subfloor
residential sump pumps will stop when most needed.
So perhaps buy a few petrol driven pumps, but the problem there its
unlikely they would be maintained and would lie idle in sheds for 5
years say, and not run when required.
So how high a capacity/throughput/amperage of pumps using 12volt (from
car batteries) and-a where can they be obtained eg for-a large garden
water features perhaps, ie bigger than windscreen washer pumps say.
Or even perhaps-a human powered pumps capable of lifting one metre ,
efficiently by perhaps 2 people, an action like those "wild west"
railway human powered personel carriers, or old sailing ship human
powered bilge pumps, and where to obtain such.
An easy job to extend vertically the sumps, as all the same make and
size, just-a remove the covers and bolt on a small vertical extender ,
for-a access for such supplemental pump piping.

I'd have thought that car batteries (and humans) wouldn't be very well
suited for coping with the duration of a "marine surge".

Where are you going to pump it to?

I'd look for a second hand trash pump or similar and suitable lengths of
suction hose ...

The exsting "solids" pumps are 1KW rating, so far I've only come across 110 or 240V sewage/trash pumps and 12V "clean" water pumps of low amperage. Hopefully there are 12V trash-a pumps of at least 20 amps rating available somewhere, for boats or caravans perhaps. Even a quarter the power is better than nothing. Luckily the peak-a of marine surges would be less than an hour even for the lowest house, unlike rainfall/non-tidal river flooding situations which can peak for days.

Pumping to the general floodwater outside the house , like the fitted pump outlets

In a battle between humans and Mother Nature, when we look at
the score board, what percentage of the time did the humans win ???

The answer is perilously low, like 0% of the time.

My advice would be, you are somehow seriously underestimating
the situation. That would be my starting point, then I would
work backwards from there. You can have overland flooding (basement
window sills), sewerage backup flooding, and sump flooding
(crack the foundation slab).

*******

The hardware store "battery backup sump pump" kit, is for
relatively tame sump-pump emptying tasks lasting a day or less.
Because it is a sump kit, sumps usually use 1/4 to 1/3rd HP.
A horsepower is 746 watts. A 1/3rd HP motor is 250 watts.
The stall current (as the motor spins up) is 2500 watts for
about 3 seconds perhaps. When working the "continuous" consumption,
a tiny allowance should be made for the consumption during the
startup interval as the pump comes up to speed.

I could pretend the sump rate we're talking, is 40 seconds on per
ten minute (600 second) interval, and from that, you can work out a "continuous" rating for the power drawn (17 watts averaged). Maybe four batteries
in parallel, and a fairly thick cabling could power the pump. You
take your multimeter and cut off power to the pump from the
batteries, before they are discharged too low. A car battery
can be discharged 25%, so as not to damage it. A Leisure Battery
is good for 100%. If the need arises to do that ("keep running
it until the pump no longer spins"), but this is
never good for lead acid chemistry, and the only reason the
Leisure Battery has such a rating, is thicker plates, more packing
into the plates, means more abuse can be handled. The Leisure battery
might have handles on it, so two lads can lift it. During a failure,
you may need to lift the batteries to higher ground, so the
basement water is not electrified by the batteries.

My sump has a one-way valve on it. The hardware store valve, sucked.
I have a nice valve now that has lasted years and does not leak,
and I have one extra of those valves that has not been needed.
These valves were bought at the Pump House, a place that sells
all manner of items, including some sump pumps for five hundred each.
When I needed hose, for my emergency pump, they ordered some in
and cut me a hunk. That's around a 2" line, for pumping out the back yard.
150 feet of hose.

It only takes around half a day to pump out the back yard.
With the smaller pump, it takes three days to pump down the properties
around me that add their water to what I pump. And using the lower
capacity pump is smarter, as it allows the land to drain gradually
and when you stop pumping, no water starts to accumulate again
because you pumped too fast. You have to tailor your pumping style
to the situation. When pumping the inside of the house, you're
going "as fast as you can".

Even hose, there is the "I am a cheap homeowner" kind of hose,
and a "professional" suction-capable hose. You might think
that cheaping out is clever, but if the lay-flat hose you bought
rounds any sort of corner, it clamps off the flow and your hose
is useless. The suction rated hose, as long as you can manage to bend it
on a curve where it needs to go, it won't collapse on you and pinch off.

With the layflat hose, you can cut it in sections, and fit 90 degree
"fixtures + Jubilee clamps" between hose sections. Label all the
hose sections with numbers, to aid assembly in the correct order for
an emergency... and in that way, you can achieve an "I beat the system!"
rating with that cheap layflat hose you bought. But if you go to the
home depot and rent a pump and some hose, they rent you the professional hose. And you still may need a 90 degree fitting, where the hose is attached
to the pump. (If you are emptying a swim pool, you don't need a 90,
while setting up for overland flooding pumping you might need a 90,
and you can rent the 90 degree fitting too.)

Your hose may crack with age, depending on quality, and if you haven't
used it for a number of years, it pays to take it out of doors,
connect the garden hose to it and pressurize it a bit (not 120 PSI)
for a test. Don't overdo it, but at least check it does not have openings in it.
I have an adapter so I can connect the garden hose to the larger
hose samples. You also need garden hose water, when flushing a line
after using it with dirty water. Not on the expectation you will
be drinking from the hose, just to give it one less excuse to fail.
Drain the hose well as you wind it up (for the layflat kind).

For serious prospective flooding, you need to be a sandbagger.
And not everyone is gifted enough to build a good wall. Lots
of failures. Don't ask me how to build one of those that does
not leak. But occasionally a homeowner becomes famous, for making
one that didn't leak. It makes you want to give them an
engineering degree. For the rest of the ordinary people, the
purpose of the sandbags is to reduce the size of pump needed,
but not expect your island to be water tight. In a real flood,
on a loss of mains, any battery sort of gadget would have died long
ago, before the flood level drops. You'd need a petrol pump for
a steady leak, and a way of buying fuel (petrol stations also lose
their AC and cannot provide fuel when there is no AC). Even our
tank farm did not have sales capability, as there was no electricity
to run the cash registers.

My property has lots of leakage paths, and if I build a sandbag
wall around the house, the water would find its way to the weeping
tile (even though it should not be able to do that), and water
would be coming into the sump at a ferocious rate. This is what
I mean about thinking and planning. There are lots of failure
cases to consider. Nobody thinks of all of them. That's why
as humans, our win rate against Mother Nature is 0%.

Paul
--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: uk.d-i-y

On 12/01/2026 22:11, Paul wrote:

n a battle between humans and Mother Nature, when we look at
the score board, what percentage of the time did the humans win ???

The answer is perilously low, like 0% of the time.

I give you the East Anglian fens.
--
Climate Change: Socialism wearing a lab coat.

--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: uk.d-i-y

On 12/01/2026 22:11, Paul wrote:

On Mon, 1/12/2026 2:03 PM, N_Cook wrote:

On 12/01/2026 16:57, Andy Burns wrote:

N_Cook wrote:

We've recently found out that in the very near future with any marine >>>> >>>surge flood about 0.1m higher than the one in 2024, SSEN would pre- >>>> >>>emptively remotely cut the local electricity supply to protect their >>>> >>>lowest local substation transformer. So the 30 or so subfloor
residential sump pumps will stop when most needed.
So perhaps buy a few petrol driven pumps, but the problem there its >>>> >>>unlikely they would be maintained and would lie idle in sheds for 5 >>>> >>>years say, and not run when required.
So how high a capacity/throughput/amperage of pumps using 12volt (from >>>> >>>car batteries) and where can they be obtained eg for large garden >>>> >>>water features perhaps, ie bigger than windscreen washer pumps say. >>>> >>>Or even perhaps human powered pumps capable of lifting one metre , >>>> >>>efficiently by perhaps 2 people, an action like those "wild west"
railway human powered personel carriers, or old sailing ship human
powered bilge pumps, and where to obtain such.
An easy job to extend vertically the sumps, as all the same make and >>>> >>>size, just remove the covers and bolt on a small vertical extender , >>>> >>>for access for such supplemental pump piping.

I'd have thought that car batteries (and humans) wouldn't be very well >>> >>suited for coping with the duration of a "marine surge".

Where are you going to pump it to?

I'd look for a second hand trash pump or similar and suitable lengths of >>> >>suction hose ...

The exsting "solids" pumps are 1KW rating, so far I've only come across 110 or 240V sewage/trash pumps and 12V "clean" water pumps of low amperage. Hopefully there are 12V trash pumps of at least 20 amps rating available somewhere, for boats or caravans perhaps. Even a quarter the power is better than nothing. Luckily the peak of marine surges would be less than an hour even for the lowest house, unlike rainfall/non-tidal river flooding situations which can peak for days.

Pumping to the general floodwater outside the house , like the fitted pump outlets

In a battle between humans and Mother Nature, when we look at
the score board, what percentage of the time did the humans win ???

The answer is perilously low, like 0% of the time.

My advice would be, you are somehow seriously underestimating
the situation. That would be my starting point, then I would
work backwards from there. You can have overland flooding (basement
window sills), sewerage backup flooding, and sump flooding
(crack the foundation slab).

*******

The hardware store "battery backup sump pump" kit, is for
relatively tame sump-pump emptying tasks lasting a day or less.
Because it is a sump kit, sumps usually use 1/4 to 1/3rd HP.
A horsepower is 746 watts. A 1/3rd HP motor is 250 watts.
The stall current (as the motor spins up) is 2500 watts for
about 3 seconds perhaps. When working the "continuous" consumption,
a tiny allowance should be made for the consumption during the
startup interval as the pump comes up to speed.

I could pretend the sump rate we're talking, is 40 seconds on per
ten minute (600 second) interval, and from that, you can work out a "continuous" rating for the power drawn (17 watts averaged). Maybe four batteries
in parallel, and a fairly thick cabling could power the pump. You
take your multimeter and cut off power to the pump from the
batteries, before they are discharged too low. A car battery
can be discharged 25%, so as not to damage it. A Leisure Battery
is good for 100%. If the need arises to do that ("keep running
it until the pump no longer spins"), but this is
never good for lead acid chemistry, and the only reason the
Leisure Battery has such a rating, is thicker plates, more packing
into the plates, means more abuse can be handled. The Leisure battery
might have handles on it, so two lads can lift it. During a failure,
you may need to lift the batteries to higher ground, so the
basement water is not electrified by the batteries.

My sump has a one-way valve on it. The hardware store valve, sucked.
I have a nice valve now that has lasted years and does not leak,
and I have one extra of those valves that has not been needed.
These valves were bought at the Pump House, a place that sells
all manner of items, including some sump pumps for five hundred each.
When I needed hose, for my emergency pump, they ordered some in
and cut me a hunk. That's around a 2" line, for pumping out the back yard. 150 feet of hose.

It only takes around half a day to pump out the back yard.
With the smaller pump, it takes three days to pump down the properties
around me that add their water to what I pump. And using the lower
capacity pump is smarter, as it allows the land to drain gradually
and when you stop pumping, no water starts to accumulate again
because you pumped too fast. You have to tailor your pumping style
to the situation. When pumping the inside of the house, you're
going "as fast as you can".

Even hose, there is the "I am a cheap homeowner" kind of hose,
and a "professional" suction-capable hose. You might think
that cheaping out is clever, but if the lay-flat hose you bought
rounds any sort of corner, it clamps off the flow and your hose
is useless. The suction rated hose, as long as you can manage to bend it
on a curve where it needs to go, it won't collapse on you and pinch off.

With the layflat hose, you can cut it in sections, and fit 90 degree "fixtures + Jubilee clamps" between hose sections. Label all the
hose sections with numbers, to aid assembly in the correct order for
an emergency... and in that way, you can achieve an "I beat the system!" rating with that cheap layflat hose you bought. But if you go to the
home depot and rent a pump and some hose, they rent you the professional hose.
And you still may need a 90 degree fitting, where the hose is attached
to the pump. (If you are emptying a swim pool, you don't need a 90,
while setting up for overland flooding pumping you might need a 90,
and you can rent the 90 degree fitting too.)

Your hose may crack with age, depending on quality, and if you haven't
used it for a number of years, it pays to take it out of doors,
connect the garden hose to it and pressurize it a bit (not 120 PSI)
for a test. Don't overdo it, but at least check it does not have openings in it.
I have an adapter so I can connect the garden hose to the larger
hose samples. You also need garden hose water, when flushing a line
after using it with dirty water. Not on the expectation you will
be drinking from the hose, just to give it one less excuse to fail.
Drain the hose well as you wind it up (for the layflat kind).

For serious prospective flooding, you need to be a sandbagger.
And not everyone is gifted enough to build a good wall. Lots
of failures. Don't ask me how to build one of those that does
not leak. But occasionally a homeowner becomes famous, for making
one that didn't leak. It makes you want to give them an
engineering degree. For the rest of the ordinary people, the
purpose of the sandbags is to reduce the size of pump needed,
but not expect your island to be water tight. In a real flood,
on a loss of mains, any battery sort of gadget would have died long
ago, before the flood level drops. You'd need a petrol pump for
a steady leak, and a way of buying fuel (petrol stations also lose
their AC and cannot provide fuel when there is no AC). Even our
tank farm did not have sales capability, as there was no electricity
to run the cash registers.

My property has lots of leakage paths, and if I build a sandbag
wall around the house, the water would find its way to the weeping
tile (even though it should not be able to do that), and water
would be coming into the sump at a ferocious rate. This is what
I mean about thinking and planning. There are lots of failure
cases to consider. Nobody thinks of all of them. That's why
as humans, our win rate against Mother Nature is 0%.

Paul

As far as sewage back up, a solution is on this site

https://itchentides.wordpress.com

on the PLP section on the top menu.
A simple retrofit non return valve for existing 4inch sewer pipe at a
manhole. I made and installed one a year or 2 back and its not trapped
any normal usage material . No area wide sewage back up in that time and whetherits stopped rats in that time, well none have got in if they
tried (a local report of one seen in a nearby 3inch sewer, previosly)
--
Global sea level rise to 2100 from curve-fitted existing altimetry data <http://diverse.4mg.com/slr.htm>
--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: uk.d-i-y

N_Cook <diverse@tcp.co.uk> wrote:

As far as sewage back up, a solution is on this site

https://itchentides.wordpress.com

on the PLP section on the top menu.
A simple retrofit non return valve for existing 4inch sewer pipe at a manhole. I made and installed one a year or 2 back and its not trapped
any normal usage material . No area wide sewage back up in that time and whetherits stopped rats in that time, well none have got in if they
tried (a local report of one seen in a nearby 3inch sewer, previosly)

What design did you use? I've been looking at NRVs and the only retrofit design on the market I can find is this one:

https://www.drainagecentral.co.uk/Flexseal-Retrofit-Non-Return-Valve-110mm-NRV4

(also called 'Buffalo' or 'Metex')

It seems NRVs can be troublesome as they can get clogged with toilet paper
etc, and also cause problems in that water can then back up into the house.
I'm not particularly thrilled with the flap design on that one.

Theo
--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: uk.d-i-y

On 12/01/2026 19:03, N_Cook wrote:

So how high a capacity/throughput/amperage of pumps

and

of low amperage.

The word you want is power as in "capacity/throughput/power" or "low power".

If you wish you could say "high current consumption".

In a 40+ year electrical/electronics career, nobody (in the UK) used the
word amperage. Unless they wanted to be laughed at. Especially by my Motors/Generators professor.


--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: uk.d-i-y

On 13/01/2026 10:46, Theo wrote:

What design did you use? I've been looking at NRVs and the only retrofit design on the market I can find is this one:

https://www.drainagecentral.co.uk/Flexseal-Retrofit-Non-Return-Valve-110mm-NRV4

(also called 'Buffalo' or 'Metex')

It seems NRVs can be troublesome as they can get clogged with toilet paper etc, and also cause problems in that water can then back up into the house. I'm not particularly thrilled with the flap design on that one.

Theo

Off-the-shelf commercal NRVs for 4inch sewers are for new fit, they are useless for retrofit because of the benching in the bottom of any manhole .

I would not say design for my retrofit NRVs, ust using what is easily available locally ,the text on that Itchentides site
"
Mark 2 version of DIY 110/100mm NRV

Starting with a toilet pan connector, preferably the angled outlet
version available from Wickes etc.

The angled closing face means the aluminium panel is less like to snag
on any benching. Remove the rubber jointing section for the outlet pipe.

Cut back the fibre reinforced plastic back to the angled face and leave
a suitable periphery flange to accept an aluminium sheet cut down to a matching size. Create a hinge from stout copper wire from cooker cable.

Also cut a sheet of silicone rubber to match the aluminium.

"
In the pic its not so obvious the tilted plane of the angled connector.
The bend at the top of the aluminium sheet is to allow a simple pivot of
2 holes drilled at the bend and stout copper wire forming 2 loops as the hinge.
A monthly "scouring flush" down a toilet may be avoiding paper build up.
Even without an NRV, with metered water supply , cistern hippos etc,
less water generally keeping the 4inch piping clean, a scouring flush regularly is good practise.
Scouring flush is a bucket of grey water chucked down the pan along with cistern flush , chucked at an angle to create a swirl/vortex of water.
--
Global sea level rise to 2100 from curve-fitted existing altimetry data <http://diverse.4mg.com/slr.htm>
--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: uk.d-i-y

N_Cook <diverse@tcp.co.uk> wrote:

On 13/01/2026 10:46, Theo wrote:

What design did you use? I've been looking at NRVs and the only retrofit design on the market I can find is this one:

https://www.drainagecentral.co.uk/Flexseal-Retrofit-Non-Return-Valve-110mm-NRV4

(also called 'Buffalo' or 'Metex')

It seems NRVs can be troublesome as they can get clogged with toilet paper etc, and also cause problems in that water can then back up into the house. I'm not particularly thrilled with the flap design on that one.

Theo

Off-the-shelf commercal NRVs for 4inch sewers are for new fit, they are useless for retrofit because of the benching in the bottom of any manhole .

The above is a retrofit that should in theory fit the benching as there is
no collar around the flap, but I'm not thrilled by the construction.
There's also the Capricorn:

https://www.amazon.co.uk/dp/B0CV5YT4WF

That looks sturdier, but I suspect it's not going to fit, and even if it did
go in you'd need a bit of pipe inside the clay/etc drain to mount it to.

I would not say design for my retrofit NRVs, ust using what is easily available locally ,the text on that Itchentides site
"

Ah, thanks. The 'Living by the river' -> 'Property level flood protection' section of the website doesn't have any links. Some are linked from here:

https://itchentides.wordpress.com/to-test-and-fix-plp/

In the pic its not so obvious the tilted plane of the angled connector.
The bend at the top of the aluminium sheet is to allow a simple pivot of
2 holes drilled at the bend and stout copper wire forming 2 loops as the hinge.
A monthly "scouring flush" down a toilet may be avoiding paper build up.
Even without an NRV, with metered water supply , cistern hippos etc,
less water generally keeping the 4inch piping clean, a scouring flush regularly is good practise.
Scouring flush is a bucket of grey water chucked down the pan along with cistern flush , chucked at an angle to create a swirl/vortex of water.

Hmm, homemade is not for me as they have to go in the manhole of the main sewer. If they fall out they block the sewer for everyone upstream, which
is a lot of houses.

Theo
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From Newsgroup: uk.d-i-y

N_Cook <diverse@tcp.co.uk> wrote:

We've recently found out that in the very near future with any marine
surge flood about 0.1m higher than the one in 2024, SSEN would
pre-emptively remotely cut the local electricity supply to protect their lowest local substation transformer. So the 30 or so subfloor
residential sump pumps will stop when most needed.
So perhaps buy a few petrol driven pumps, but the problem there its
unlikely they would be maintained and would lie idle in sheds for 5
years say, and not run when required.
So how high a capacity/throughput/amperage of pumps using 12volt (from
car batteries) and where can they be obtained eg for large garden
water features perhaps, ie bigger than windscreen washer pumps say.
Or even perhaps human powered pumps capable of lifting one metre , efficiently by perhaps 2 people, an action like those "wild west"
railway human powered personel carriers, or old sailing ship human
powered bilge pumps, and where to obtain such.
An easy job to extend vertically the sumps, as all the same make and
size, just remove the covers and bolt on a small vertical extender ,
for access for such supplemental pump piping.

I'd have thought you would be looking at multi-kW pumps. eg the first hit
for a petrol pump is a 4kW / 5.5hp unit that does 966 l/min: https://hyundaipowerequipment.co.uk/hyundai-hy80-80mm-3inch-petrol-water-pump

For that I think you're into mains pump territory, as 4kW would be wanting
333A from a 12V battery. I can think of two possible ways to work it.

One is petrol or diesel generators. Going to source more fuel is likely feasible assuming you aren't trapped by the floodwaters, and you can keep a good amount in stock (plus can rotate it through a car to keep it fresh). A variation is natural gas generators, assuming the gas supply holds up.
You'd likely have to run the generator occasionally to check it's still working, but you could run power into an electric heater rather than the
pump.

Another is electric cars that have a mains output ('vehicle to load' or
V2L). Again assuming the roads are still feasible, you get let's say 15
hours on a 60kWh battery and then have to take a car away to recharge it.
Of course that is less good if it lets the waters rise while it is away, so
you might need a way to share the outputs while one car out of N goes to recharge. At least this 'generator' gets tested regularly through usual
usage. Downside is many V2L outputs are limited in kW.

Both have the advantage you can power other things during a flood,
not just the pump.

Theo
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