I would not expect every tap to supply potable water. The law only requires that there is one tap connected to the mains. In a domestic premises that should be the cold tap over the kitchen sink. All others should be treated as likely to be fed from a cistern, unless you definitely know to the contrary.
Until a few years ago *none* of the taps here where on the mains, the mains only went to 3 x 50 gallon storeage tanks in one loft. A few years ago some of the hot taps went onto the mains. A couple of months ago some of the cold joined them.
I use IBCs to harvest rainwater off a stable roof to supply water manually to the horses. I don't have a problem with larvae, but I *do* use the floating "chlorine dosing" thingies what you can use in garden pools to suppress the level of algae.
I assume that this is what deals with the larvae too.
At another livery yard where I ride, they have a large open water container of a couple of thousand litres which is fed either from towns mains or from a local bore hole (not sure which). They keep a handfull of goldfish in this, which deals very effectively indeed with the larvae (although it does get fairly "green").
I am using 10 IBCs, 5 vertical stacks of two if that makes sense.
The upper level of tanks will be connected to its tank below. So the idea being with 10 off 600 littre IBC's I can store up to 6000 litres of water.
The bottom 5 tanks will be connected via a "bus bar" pipe so to speak and tank breathers fitted to all 10 IBCs.
SO I can either use a submersible pump in one of the bottom tanks or use an external pump connected to the "bus bar" pipe.
Well, Although I do still have a 250 litre plastic tank in the loft which is currently empty, It seems a shame to cut it up rather than use it as part of my rainwater harvesting system.
So I have two choices, either connect the house toilets and outside taps to the loft tank or connect directly via a pumped feed from the IBCs.
The only advantage I can see in usign a loft tank is that water will still be available to the toilets during a power cut. The disadvantage I can see is the risk of the loft tank freezing & bursting in deepest winter.
Thank you for that, that is worth knowing.
How small does the mesh size have to be to prevent mosquitoe larvae from entering?
Ditto the pipework....
ALl my potable cold water and hot water pipes are all in copper.
I did the rain water pipework in white plastic so its clear whats inside the pipes when floorboards are lifted
Or have a high-level switch to shut the pump off and a separate high-high-level switch to shut off the pump, lock it out and raise an alarm in case the high-level one fails.
That's what I'd do if I were planning such a system (I have thought about it a few times).
SteveW
In case this is useful...
With our extension I also had a 9m3 underground rainwater tank put under a new patio in front of the house. A large submersible pump feeds into the loft via pipework passing through standard 100m drainpiping also carrying the cables.
The pump runs automatically on back pressure and I have pipework going around the garden and to top up the ponds etc.
In the loft the water feeds into a header tank for the three toilets in the house. It was recommended to me *not* to use a ball-c*ck valve as these can dribble, switch on and off very slowly, and generally not be good for the pump.
It's better to have something which switches cleanly.
So, what I did was to use a solenoid valve and a simple relay circuit of my own design to control the valve using a couple of float switches in the header tank for the high/low levels.
There *is* also a ball-c*ck valve but this is positioned such that it only closes when the header tank is about to overflow and is well above the float switch level - this is in case the float switch or my electronics goes wrong and the pump keeps topping up the header when it shouldn't. Normally the ball-c*ck valve is fully open and therefore "clean" running.
What's more, I also rigged up a *second* input into the header tank so that mains water would feed into it.
There is a third float switch just below the low-level switch such that if the water goes below that level it must mean that the rainwater pump is not topping up the header tank. When this happens the electronics switches on the second solenoid valve to top-up using mains water (until the upper float switch level is reached). Therefore there can be no interruption to toilet water if it doesn't rain.
Double belt and braces.
Michael
Yes, but the original source of the water in the cold-water tank would have been treated mains water. I know all sorts of horrors can be found in loft tanks which aren't covered (many years ago I lived in a block of flats where pigeon feathers suddenly appeared in the tap water!), but most people don't know they should really not use bathroom basin tap water for cleaning their teeth, or they ignore it. Rainwater would have far more nasties than anything from a loft.
In any case, I have never seen an outside tap which ran from anything other than mains water, as the pressure from a local tank would be too low for most hoses.
Some friends of mine used to live in a farmhouse in West Wales, and their water came from a well. It came to the house via copper pipes, and there were blue stains under the taps on the porcelain sinks!
Isn't it more the case that the bathroom basin tap should be fed from the rising main?
Chris
It is only required that one tap be connected to the mains, which should normally be in the kitchen. Connecting the bathroom basin tap to the mains is recommended, but not required.
White plastic pipe is intended for domestic waste water, so most people would assume it to be empty unless something was actively running to waste. Grey BS 3050 pipe would be a better choice as being something not normally found in domestic installations. Also, if the water is being pumped. BS 3505 pipe is pressure rated, while white waste pipe is not.
Alternatively, you could apply British Standard identifying colours along the length of the pipes, to show what is in them. For drinking water, the colours are three equal width bands of green, blue and green respectively. For rainwater, the two outer green bands remain, but the blue one is replaced by three equal width bands of grey, black and grey.
It would also allow you to have an alternative mains feed to that cistern that you could turn on, so that you could continue to use the toilets when you didn't have enough rainwater.
That is why a cistern in the loft should be well insulated on top and sides and without insulation under it.
Out predecessors in this house fitted an outside tap to the tank water !!!
It ceases to be potable water as soon as it is stored.
My business is supplying screens for overflow pipes, to prevent the less obvious problem of insects flying up them and carrying infection into the water supply. That is an important vector in the spread of Legionnaires disease, for example.
That depends very much upon how it has been handled. Raw rainwater is likely to contain a lot of rubbish. A system that rejects the first run off from a dry catchment area and passes the rest of the water through a series of settlement tanks and filters, should produce fairly clean water.
It probably wouldn't work a sprinkler, but I happily run a seeper hose off a rainwater butt. It just takes longer than if it were connected to the mains.
Nightjar posted
How many times has that happened in a domestic context in the UK?
is that a problem with an open top tank?
NT
No idea, but obviously it is considered enough of a risk for the Water Byelaws and their successors to have required for decades that domestic water cisterns be insect proof.
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