Filling toilet cistern with rainwater

[petec]

I like the lo-tec bucket solution, but guests might not appreciate it - there's also the hassle of keeping the bucket filled.

OK, here's how someone could make a fortune. Design a double cistern - mains feed with HP valve on one side, rainwater feed with LP valve on the other. 2 flush levers - you flush with rainwater unless there's none available in which case you flush with mains. In these eco-conscious water saving days it would be a definite success. No pumps required, though only suitable for downstairs toilets where you can get enough height on the water butt. If smell really was a problem, I'm sure something could be put in that side of the cistern to neutralise it.

What do you think?

 

[muggles]

Can we just take a step back here for a second...what is it you're actually trying to achieve? Because this is rapidly getting more complicated/expensive and it'll take forever to repay the cost involved, especially if you crack the cistern when you're trying to drill it.

 

[petec]

See top of this thread. The idea's a simple one - to use rainwater for flushing when there's enough in the waterbutt outside (wall mounted higher then the cistern), or switch to mains when there isn't. The obstacle seems to be having an inlet valve which can cope with HP from the mains and LP from the waterbutt. 2 separate entries is one solution, but on my particular cistern there are no alternative entry points.

 

[Bon]

Can't see what the problem is, why bother with a mains feed, it's not as if you'll need it in this weather!!.

Back on topic though, Pete, you're in luck.

I designed a system the other week for a service station WC block (OK it's a larger scale than your downstairs loo, but the principle is the same!!)

Run a mains feed to the water butt to the water butt, not the cistern will be easier to drill than your cistern too and fit the double check valve to this as the mains will be able to open it, plus you'll get a type-A air gap to make back-flow even less likely. You can then get the LP cistern inlet.

The only problem I can think of with your system is that on the one I did I used a 2-way valve with a solenoid connected to a level switch at the bottom of the tank which opens up the mains supply if there's less than 10% of the tank's volume there. This could prove costly if it's just for one cistern.

I suppose you could get a bit Heath Robinson and fashion an extended float rod to drop to the bottom of your tank? You'd just have to be careful it didn't twist sideways and over-flow your tank.

 

[tryitandsee]

The Gibraltarians (Gibraltar) used to collect rain water off the 'rock', via a large collection area in Catalan Bay (made of corrugated iron panels) and I think they used this for WC flushing. They may have mixed this with salt water, not sure, but the water to the cisterns was separate from the drinking water. It must have been expensive running a two pipe supply, but when drinking water used to be brought in by sea tankers, it must have been economic at the time.

 

[tryitandsee]

Got my facts slightly wrong. Not relevant but quite interesting.

In 1869 ground water exploration was initiated by Mr E Roberts, Engineer to the Sanitary Commissioners. A sandy aquifer was found at the isthmus, which links Gibraltar to Spain. Wells were constructed and a pump house and pumping system built to convey this water to public reservoirs at Moorish Castle and Europa Road areas. The water from these wells became brackish very quickly and was used mainly for sanitary purposes; the water collected from rains being used for dietetic purposes. From this developed our unique system of dual water supplies whereby there are two supply and distribution systems; one for potable water and the other for seawater. Seawater is used for fire-fighting, street flushing, sewer flushing and other sanitary purposes where the use of potable water is not essential. Every house enjoys a supply of salt water paid for under the "Rates" and a supply of potable water that is metered and billed for on a monthly basis. This dual supply system reduces the amount of potable water required by over fifty percent. It is interesting to note that water, from the condensers of steam machinery used to lift seawater to various reservoirs, provided some 45.5 cubic metres of distilled water per annum in the late 1800's and was the first attempt in Gibraltar to produce fresh water from the sea.

 

[Technotim]

This is a eco friendly little gadget

.
got it from http://www.rainwaterharvesting.co.uk/

There wording say's

Solar Pump starter kit Details

The Solar Powered Pump kit enables you to use rainwater in the house and round the garden without using mains electricity.

I am going to be starting a new Eco business later this year and found it doing research.

 

[petec]

I like Bon's cold feed to waterbutt solution which possum_jenkins also mentioned earlier. Presumably this would work with a bottom entry Torbeck valve for shutting off. The beauty of this solution being that you don't need to be bothered with switching feeds - just flush the loo, and it's up to the weather where the water comes from. I may do this once I've monitored how often (if ever) the rainwater runs out.

In the meantime, I've put in a new Torbeck in the cistern this morning having removed both the HP restrictor (over 4 bar) and the LP (1-4 bar), and can report that it appears to work perfectly, refilling reasonably quickly. For the time being I've left the mains feed connected too, shut off with a lever ball valve. Can anybody see a reason why I shouldn't refill by just opening this a fraction if the waterbutt empties? I realise that technically this is restricting the flow, not the pressure, but are they effectively the same thing as far as the Torbeck is concerned?