(Simple!) rainwater harvesting system

[pontiff]

I'm only in the planning stage here so all thoughts appreciated!

I want a simple system to supply rainwater to downstairs toilet.

I'm thinking Water butt/tank (size? Two adults in house)

12v pv powered pump ( got spare one from my canal boat- shurflo with built in pressure switch)

 Got a 60w pv panel knocking about in the shed - attach it to charge controller and leisure battery),

Expansion tank  to stop pulsating when filling.

Attached direct to the cistern via lagged pipe mostly buried apart from where it enters downstairs bathroom through wall .

I would like to keep the mains supply as an emergency backup ( in case I have to drain down rainwater supply if in danger of freezing). Am I right in thinking this needs to be physically disconected when not in use as opposed to having a valve arrangement (water regs/ air gap ?)

I know this is a tiny project compared to some of the monsters on this forum but it would be a start and hopefully inspire me to scale up massively in the future.

Any thoughts/ advice greatly appreciated.  

forgot to mention downpipe filter connected to water tank plus a filter before the pump

[feeta]

Hi Pontiff, I`m sure someone else may be along soon to help but for the meantime...

I`m looking into a similar system at the moment. It`s not exactlyhow your describing your system but similar.  You are right about water regs.  Contaminated water must not come into contact with mains water.

The way I`m going to get around this is by having a header/collector tank in the loft.  This is fed from the waterbutt outside via a 12v pump charged from PV.  The header tank in the loft feeds the toilet cisterns only. This header tank has a float switch.  If water level drops below the float switch, the pump turns on until the header tank is refilled.  However, as a backup, the header tank also has a ball valve connected to the mains.  It is very important that this ball valve is a minimum of 15cm above the overflow of the header tank. This is to meet with water regs.  Basically, if there is water in the water butt when the header tank calls for it, it is pumped up.  If there is no water in the butt, the pump will not turn on and the water level in the header tank will drop.  This will bring the ball valve into play and put mains water into the header tank.

Hope that helps a little.

Feeta

[daftlad]

It is very important that this ball valve is a minimum of 15cm above the overflow of the header tank. This is to meet with water regs.

As I understand it you can not use a standard overflow because if it gets blocked there is still a possibility of water coming into contact with the ball valve inlet.
A "weir" arrangement is required as an overflow. I saw a picture on this forum of a tank sat in a home made tray with a plug hole, the tank had some of one side cut out, so if the tank overfilled it would overflow into the tray.
All this is based on what I have read here, see I was concentrating.
ta ta

[pipesmokingman]

hi guys - right well having done this already - my 10 pence worth -  - first things first -water buts are fine -BUT depending on how many people you have in the house and how much they use the loo ( obviously ) - you will find that at say 10 Lt per flush  - even a large butt will drain fairly quick - ( which is why my next move with my system is an IBC of at least 1000 Lt's - and i would say that for "reliable" all year round capacity for ONE PERSON this is minimum

float switches - header tanks etc - yep again fine - IF you want to over complicate things - i have a simple switch ( with one of those sexy red "missile fire " covers ) - that stops and starts the pump ( 12 volt - solar powered via battery bank ) - end of - ya want water ?? - then stand there and fill the cistern

as to back flow / contamination - nooo chance as the mains supply to the loo is  physically VALVED OFF + i always use non return valves in line  -( what you want MAINS  on for when on rain ?? ) - the rain water inlet is below the mains float valve which then ALSO acts as a seal  as it is shut by the rain water acting on the float valve ( also a good way of using less water to flush ) - and it auto flushes the line if you have to change over ( think about it )

( water regs - wot they then ??  - like ALL rules they are for " the adherence of fools and the guidance of wise men " and what the rob dogs at our local water board don't know - don't hurt them )  ***

and something else i have learned this winter - insulation is king for outside storage tanks if above ground !! - - so a rehash is required this summer to stop any problems next year - but that's all part of the learning curve with this stuff

and finally - you MAY want to do some guttering diversion - any roof area that's NOT  contributing - is wasted collection - all my roofs ( shed -garage etc ) have been diverted - now if i could figure some way of getting the guttering at the front of the house to discharge at the back  ..........

any ways - good luck with your projects - the scope for invention and bodging is enormous - and even my small system saves me a fortune in metered water - well why pay to flush it away ??

*** - best to keep quiet about what you do with this ( don't advertise) as if the penny pushers at the water mafia HQ hear of too many people doing this sort of thing ( usually via nosy and interfering neighbors ) - then they will be demanding to inspect installation and there will be rules regs and even MORE  charges coming out of our ears - well THEY OWN  all the water that falls out sky ( apparently in some states of the US you are not allowed to rainwater harvest ) - WHO THE HELL gave them THAT right then ?? 

makes me laugh - when there ain't enough of it they own it all - and when there's too much ( eg flooding ) - oh then its not their responsibility but an act of god - may be WE should start charging THEM if we get flooded for looking after THEIR  water ??  - don't get me started ................

[Greenbeast]

now if i could figure some way of getting the guttering at the front of the house to discharge at the back  ..........

do you live in a detached house or a semi?
Can't you just put more guttering along the side of the house from the front to the back and remove the front downpipes?

[pontiff]

as to back flow / contamination - nooo chance as the mains supply to the loo is  physically VALVED OFF + i always use non return valves in line  -( what you want MAINS  on for when on rain ?? ) - the rain water inlet is below the mains float valve which then ALSO acts as a seal  as it is shut by the rain water acting on the float valve ( also a good way of using less water to flush ) - and it auto flushes the line if you have to change over ( think about it )
 
( water regs - wot they then ??  - like ALL rules they are for " the adherence of fools and the guidance of wise men " and what the rob dogs at our local water board don't know - don't hurt them )  ***

Thanks for all the replies, lots to think about. I am a big fan of keep it simple so I wanted to avoid the header tank option for the moment as that would mean big changes to my plumbing.. I'm sure at a later stage whe I upscale that is the route I will take.

I get the impression that "physically valved off "( although I'm sure is absolutely effective) is not sufficient for the water police  in the UK which is a pain as I would really just like to flick a switch to return to mains water if necessary. I'm not a huge fan of regs but I want to do this right.

I see now how important the size of my butt is.   1000l seems to  be about minimum if I want to do this properly according to my beer mat calculations.

Thanks once again for the replies so far... I'll let you know how I get on when the weather improves enought to venture out.

Regards,
Pontiff

[dhaslam]

I would like to keep the mains supply as an emergency backup ( in case I have to drain down rainwater supply if in danger of freezing).

There shouldn't  be any danger of freezing if the tank is deep enough and  the  water drains back into the tank when the pump is off.  The main thing is to have a very big storage tank so that water doesn't run out in dry periods.     The house I was born in had  gravity fed system from the  roof to a tank  at first floor level that fed the downstairs toilets and cold taps.   A large  tank  in the attic was  fed by a pump, originally a  single cylinder petrol engine dating back to the 1920s.   Drinking water was taken from the well by bucket.   The problem in the past was not with tanks freezing but the  pipes in the attic and in parts of the house would freeze.  Is is a mystery why  otherwise resourceful people in the past didn't see the need for insulation.   

[pipesmokingman]

now if i could figure some way of getting the guttering at the front of the house to discharge at the back  ..........

do you live in a detached house or a semi?
Can't you just put more guttering along the side of the house from the front to the back and remove the front downpipes?

terraced unfortunatly - but still pondering this one 

[Contadino]

Regarding mains backup should the level in the butt run low, mightn't it be easier to put a float switch low in the butt (the fill can be right at the top), rather than the header tank?  That way, you'd simplify the indoor plumbing.

[petertc]

 If you ave a look at this link to the pictures of the system that i have it looks like a similar setup to what you are looking for.

http://www.navitron.org.uk/forum/index.php/topic,4588.0.html

my mains back up manual
i have a washing machine elbow fitted to the tank with a hose lock connector on the washing machine end then a small length of copper pipe that allows the water to drop into the tank, there is a 100 mm gap from the top of the tank inlet to the outlet of the copper pipe so there can be no possibility of cross contamination.

Now the other thing i was think of which i have if the pipes freeze up ( not had to use it yet)
See attached picture of schematic ( not sure if this is legal but there is an air gap ) .
turn of valve one and turn on washing machine valve 1 and then you are taking mains water into the pump but maintaining an air gap.
I have this in the garage ready to go encase things get frozen up

[pontiff]

Very nice system Peter, I'm amazed it didn't freeze in the recent weather. To make things easy I'd prefer not to have to bury the tank too but maybe in the grim Yorkshire climate I might have to.

There is plenty of scope for bodging on my project... I'm getting twitchy!!

[pipesmokingman]

why not just make a little "shed " for the tank and get some polystyrene insulation or similar to lag it with ?? couple of inches all round should do it i would think - ,and sheets of 4 inch poly ain't that expensive  - i have some tanks in an unheated and uninsulated out house area and they did not freeze - just the ones directly outside exposed to the wind and cold ( all thawed out now ) - but if/when i find an IBC it will have its own little building to live in and the feeds will be taken in with plenty of insulation  ( we don't see - 6-8 down here near the coast very often fortunately )

just spent the evening moving 2 of the outside tanks inside  and re plumbing them - which will give me longer if the weather turns nasty again this year ( don't see it happening down here realistically - but i may be wrong ) - more likely a long hot /dry spell and no rain - having had the worst winter for years 

and bodging ?? yep once you get the itch - ya just gotta scratch it 

[Contadino]

Very nice system Peter, I'm amazed it didn't freeze in the recent weather. To make things easy I'd prefer not to have to bury the tank too but maybe in the grim Yorkshire climate I might have to.

There is plenty of scope for bodging on my project... I'm getting twitchy!!

How about semi-buried, with something like a Virginia Creeper growing around and above it?  If you're anticipating temps below -10, maybe cover with EPS sheeting, about 40mm thick.