High throughput water pumps (not 240volt) availability

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

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.

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

I give you the East Anglian fens.

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

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:

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

and

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.

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

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:

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:

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

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:

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