Power cuts and mains water

[Theo]

Does anyone have any experiences what happens to mains water when there is a power cut? We have switched from a cold water tank to everything being on the mains (unvented cylinder, toilets, etc), and I'm wondering how resilient this is.

Do pumping stations generally have backup power? How long might it expect to last?

I hear various media reports of past issues, but I'm unclear if this is a major event when the backups fail (run out of fuel, can't be refilled because there's a major incident, etc), which is a rare event, or simply that the moment the power goes the mains water also stops?

We are in a rural area, relatively high up compared with the surrounding land so I think we're pumped, although there are also some water towers a few miles away. I can't think of any reason why our pumping station might get out-of-the-ordinary treatment (no important facilities nearby)

Thanks Theo

[Martin Brown]

Answers based on what happened near me are no and a few minutes at most. If you want potable water you need to draw it before the power goes out.

You may be OK if you live in a valley but up a hill or on a borehole and you have had it once the electricity goes. It also caused very serious problems for the local sewage plant within 24 hours of not having power. They had to tanker stuff away.

I think it depends on where your water comes from. If there is a high up water tower then that provides little a bit of leeway but not much. A decent sized reservoir and you are probably OK (we were anyway).

Assume the worst then and draw some water ahead of the storm. Places on the moors near me were without any mains power or water for about a week after Arwen. Living in the valley definitely has its advantages. We are gravity fed from a reservoir on the moors. It didn't run out of water.

[Steve Walker]

I think that most pumping stations pumps into water towers or reservoirs that can gravity feed to their destinations.

It's not something I have really looked at, being in Greater Manchester, where our water comes mainly from Cumbria and Wales, via Victorian engineered links that work on gravity alone.

[The Natural Philosopher]

This is certainly the case here. Never had a water cut due to power outages.

[Martin Brown]

It is only really a problem for those that live high up or are on borehole pumped water supply (as we were once). It was lovely spring water but the water company decided that with no steelworks to supply they could get water for North Yorkshire much cheaper from Kielder.

It leads to a bizarre structure where water supply is from Northumbria water and sewage goes to Yorkshire water base on the watershed.

[Brian Gaff (Sofa]

Its very much a postcode lottery. Some pumps still work as they operate on other fuels, but if you are on top of a big hill, I suspect there are electric pumps in use. I was also wondering about gas and gas boilers, since they nearly all need electricity to run the electronics. Brian

[Brian Gaff (Sofa]

If you have gas and an old style ring you can boil water from a tank, indeed Inever caught anything from drinking it as it has a lid on it. Brian

[newshound]

Also here in the Cotswolds. There are several small (covered) reservoirs near the tops of the valleys around here. Once you get up into the flat bit on the top, there are a number of very obvious water towers.

[AnthonyL]

I don't believe that is how it works as it would need a double set of pipework for a start. IIRC the pumping stations pump against the water tower/reservoir pressure head and much of the water that is delivered to your tap never sees the water tower/reservoir which acts as a buffer with a low and a high point.

[Dave Plowman (News]

I resisted doing this, as even in London short term water cuts ain't uncommon. Perhaps if you use bottled water for drinking this might not matter if only a couple of hours. But I don't.

[charles]

The pumping station near here pumps UP to the reservoir from which it comes out by gravity

[Steve Walker]

But with vented water towers, the pressure in the system is still determined by the head in the tower. If the pump is pumping too much, the tower will overfill and shut the pump off. If the level falls, the pump starts. Or they may run the pump with a variable frequency drive and a PID controller, to maintain the level (and pressure) pretty well constant.

The pump still fills the tower, the tower water level determines the pressure and on failure of the pump, the tower supplies water.

I would think that they must also deliberately vary the tower water level (either by control or by not using a VFD and just turning the pump on and off) to ensure that water is partially drained from the tower and replaced with fresh on a regular basis.

[charles]

I have plenty of whisky ;-) and couple of cases of wine

[williamwright]

A power cut at the pumping station means your water will go low pressure and then stop.

Bill

[Jacob Jones]

[Steve Walker]

But we don't tend to use spherical, pressurised, steel water towers in the UK, they are often vertical cylinders, square boxes, octagonal or the like, made of lined, re-inforced concrete. The pressure is purely a function of the head of water.

[Jacob Jones]

That wasnt just about those.

I posted that in reference to your other comments about how the feed is done and the refill comments.

[Steve Walker]

Sorry I misunderstood your intent.

[Jacob Jones]

No problem, I was much too cryptic.

[The Natural Philosopher]

" The water level in the tower typically falls during the peak usage hours of the day, and then a pump fills it back up during the night. This process also keeps the water from freezing in cold weather, since the tower is constantly being drained and refilled"