Discussion
The awesome @afewbugs did a great thread on water treatment and preparation for supply interruption. It's a great thread, y'all should read it. But there's a small thing I want to add tho which I think many will find useful, and also might help understand why British plumbing is just plane weird.
Many who visit the UK will comment on how we often have independent hot and cold taps, and a lot of us who grew up in the UK were told that the bathroom tap wasn't
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@quixoticgeek My parents house had a cold water tank in the loft but the hot water tank was in the airing-cupboard in the bathroom, so the pressures were different. Hot water rises and all water falls under gravity. I don't think it relied on pressure like modern systems. We have a similar system but with the hot tank moved into the loft. A mixer-shower works fine. I only knew one house in my big family with a mixer tap in the kitchen. It took a long time to get cold water after hot there.
@quixoticgeek As a Brazilian, other than the tank always being covered (otherwise it's a breeding ground for Dengue-carrying mosquitos) that feels normal, not weird. A building or house having one or more water tanks is very common here. The water from the mains is used only to fill the tank, all taps in the house (cold or hot) come from the tank (though many places have Lorenzetti electric showers and taps instead of water heaters).
@quixoticgeek I'd have thought that most if not all now had a lid to stop that sort of thing.
Yes we still have a system like that. The last time we had the boiler changed the plumber said the water pressure was too low to install a combi boiler
@quixoticgeek most UK houses don't have a roof tank any more and either have a small hot water tank or an on demand boiler to provide hot water and direct mains water to all the cold tanks
@ianturton a lot have been removed. A lot still have them tho. Most homes I lived in in the UK have a tank still.
@quixoticgeek I last had a loft tank in the 1990s and the council came round took it out with the rest of the lead pipes to stop me dying
Modern manufacturing has improved such that mixer taps are available that can handle a mismatch in water pressure between the two sides, but that's relatively recent. Historically, you couldn't do it, so we had two taps.
But crucially, this means many British homes have a 500l tank of clean water in the roof that with a little care is available for use in the event of an emergency.
I've even seen talk that the reason this was the norm is cos cold war resilience.
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@quixoticgeek So did people brush their teeth using the bathroom tap? Did they go all the way to the kitchen for a glass of water in the middle of the night?
@msbellows one of the bonkers aspects of this system, is people brush their teeth with the water, but were also told not to drink it... It makes no sense...
@quixoticgeek I'd heard it's not Cold War resilience, but dates from much earlier times (19th century, possibly) when water supplies were intermittent. Simple "back boilers" on solid fuel appliances can be damaged if they're heated without water in them. Having a loft tank to buffer your supply means you keep water in your boiler and your non-potable cold taps.
(The rural 19th century house my parents moved into in the 1970s still had an underground water tank fed from the guttering.)
@sheddi@mstdn.party @quixoticgeek@social.v.st I think a fair amount of it would have been about regulating pressure: With a local header tank, the pressure at the taps (and, unlike with combi boilers, hot water temperature) stays more or less the same, even if someone else in the house uses water.
Not to mention that valves, compression joints and such have a much easier time of it at 0.1-0.2 bar than they do at 1-2bar. With a traditional stored system, only the ball valve in the storage tank and the kitchen tap have to handle the full mains pressure. And any solids in the incoming water (from corrosion or maintenance work on the supply pipes) tend to settle in the storage tank rather than stopping a washer from sealing properly. I expect these were all bigger issues in the past than they are today.
@quixoticgeek with the move to combi boilers and now heat pumps there's been a move away from cold storage tanks. Most places I've lived haven't had one, though some have a hot water tank. Current hot water tank requires incoming water so turning off at the mains has limited use until the pressure drops.
@quixoticgeek where we live, we don't have drinking water coming from either tap
the fact that that is somehow legal in an EU country is still absolutely baffling to me
@meena yikes. Where is that ?
@quixoticgeek hah, that is interesting — I'd not heard of that explanation/factor for the manky roof tanks before. (Per household water cache/resilience!)
Last time I mentioned the things here on Fedi I was told these tanks are getting pretty rare these days. Though two of the five homes I have rented in the UK did have this setup. (I suspect the tanks are more common in rental properties due to the lower average standard of maintenance & modernisation.)
Current place is a bungalow built in the 80s so it doesn't have that sort of setup.
The loft tanks tend to get ripped out either during (obviously) a loft conversion, or when fitting a condensing combi boiler, which doesn't need one.
The combi boiler means you can rip out the hot water cylinder as well, which allows you to gain some more space -- UK houses (particularly in towns and cities) are comparatively small, so you're always looking for whatever space gains you can get.
Of course, when you later look at fitting a heat pump, you regret ripping out the hot water cylinder...
@yvan yeah. I can't find a source for it now, but i heard it was a cold war idea to make sure everyone had a cache of water, and it meant pumps could run at a lower pressure if need be.
If your house has a tank in the loft, a really low effort, low monetary outlay bit of resilience prepping you can do is to go up into the loft, and make sure there's nothing floating in the tank that shouldn't be there, and make sure the lid is fitted properly.
In the event of that you need to rely on this water due to supply interruption, or contamination. The first thing to do is then off the water supply so it doesn't refill with contaminated water. After that you can goto @afewbugs ...
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Also make sure that water is at 60C (140° F) or above, or else what you have is a Legionella farm.
@quixoticgeek I grew up in a house that had a hot water tank as you describe, but I have to admit I haven't missed it since moving out and having on-demand boilers instead. I suppose when I move to a heat pump hot water system, I'll need a tank again, so it's nice to know it has an incidental benefit to it too.
... thread on water treatment. You can probably skip the milbank bag for the water in the loft tank (unless something has gone very wrong). But a fine filter (like a Sawyer mini), or puritabs can make the water safe to drink. All 500l of it. Which is far more than you're ever going to store in bottles in a typical home.
Final thing to add to what Jules said. There's plenty of companies on eBay selling puritabs for a lot less than Cotswolds. Everything else. Excellent advice.
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... drinking water. This is largely to do with a quirk of British plumbing. That hot tap is not fed direct from the mains water supply, but instead goes via a tank in the roof. To simplify plumbing, most bathroom taps are also fed from the same tank. Because that tank is often missing a lid to keep the dust and dead pigeons out, it's considered not drinking water. And because it's gravity fed, it's not the same pressure as the mains, which makes mixer taps a pain.
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