[tippben]

The Nenagh community garden now have a shiny new 15m polytunnel. Is there a way that it can be used to collect water, in a water butt? If so, how? The entire site has to run off one domestic tap at present, so any way we can collect and store water will be invaluable. There is 280 quid balance from the polytunnel suppliers if this would help.

[dormouse]

I haven't got it myself but I read you can get self-adhesive guttering which collects and directs the water off the cover and into whatever container you choose ...

2nd item from the bottom on page 29 ...
http://www.polydome.ie/brochures/hobbytunnels/polydome_polytunnel_pricelist_jul2011v1.pdf

Don't know how good it is. For storing the water, rather than buying lots of expensive water butts you could go with 1000 litre IBC tanks which are approx. 50 quid second hand (or even those large blue barrels). Put them in a row and use some plumbers pipe to create a syphon and daisy chain them together. So the water level will always to be equal in each one and your storage capacity would be huge.

280 quid is more than enough!

An alternative would be something like this if your tunnel design is suitable ...
http://www.youtube.com/watch?v=HevFX4NmaU8

[tippben]

I don't understand what you mean regarding the plumbers' pipe. Surely if it a siphon, it would fill the lowest container at the expense of the highest one, or are you suggesting moving the level of the pipes within the containers?

[dormouse]

No you would have all the barrels on a level. Fill one, then place one end of the pipe half way down that barrel. Have the other end outside the barrel but lower than the submersed end. Start sucking, when it starts to flow, take the next barrel, tip it over and insert the pipe. Upright the barrel but keep that end always lower than the one on barrel one. Contimue on like that. Ypu will probably need to have a hose in barrel number one to keep it filles while you are setting up the chain. But once it is done nature should take care of the rest.