[outdoorgirl]

Hi all.  We have a 40'x12' polytunnel on our site, which we got in September.  There's no mains water (there is a gravity fed system but it's rubbish), so we installed two 1000litre IBC tanks to collect the rainwater from the 6'x8' shed we have.  Even accounting for using some of this for watering the seed trays, lettuces and potted-on brassicas, we still have 600+litres in each tank atm.  

However, I'm expecting to need a LOT of water for the tunnel during the summer.  When we had our tunnel before, we had mains water so I never calculated how much we were using.

I plan to install a stick-on guttering system to collect the rainwater from the tunnel itself (you can buy these now from a couple of places, but I have a plan for a DIY job - will let you know if it's successful), and will get another couple of IBC tanks for storage.  

Our site slopes a little; the tunnel is at the bottom and the shed is at the top, so we should have some 'head' on our water tanks and can try drip hoses into the tunnel (although we are currently using a 12l sprayer atm).

My question is, for those that have a tunnel, or might be in the know - how does one calculate how much water per day would be needed for any given area?  I understand that different crops have different requirements, but an approximate average should be posible to work out?

Thanks!

Pip

[Salkeela]

I see no-one has bitten.

I have a 42'x20' polytunnel (pt) that OH & I just put up in May this year.  I didn't manage to get all the beds made so part of the tunnel was not planted this year.  Probably about half planted up.

I put large blue barrels (not sure their capacity - oil drum size?)  in the pt and used buckets from the barrels to water the beds.  At the height of the season I would have emptied a blue barrel every second day  (some-times a tad more than one barrel - I have 4 in there and always watered from the closest).

I would then fill them from the tap while doing other tasks.  OH is going to rig a new system for next year taking water from the roofs of sheds in the yard above the pt.  He hopes to join the barrels in the pt by plastic pipe and have a ball cock on one where the water comes in.  We will also have a larger water store in a container in the yard that can be used for animals etc. too.

Hope that helps.

[outdoorgirl]

Hi salkeela - thanks for replying!  From other research I've done, it was suggested that we might need about 100litres per day; your note of approx 1 blue barrel (which I think is 120-150litres) every other day for half your tunnel would bear this out.  

We don't plan to go away this summer, but if we did, it sounds like we'd be able to set up a dripper using our IBC tanks and we'd be OK for a couple of weeks, as long as we left the PT ventilated/open/shaded to avoid scorching.

I think I'll still get another couple of IBC tanks for the collection of water from the PT itself - if we get a dry summer and can't refill the tanks from our gravity feed system we'll need all the rainwater we can collect!  (Come to think of it, if we get a wet summer, I'll want to stop as much as possible from going direct into the ground and flooding my patch, so it works either way! )  

I'll keep a diary of how much we use; the tanks have graded marks so its reasonably easy to check.

Will keep everyone posted through the year!  

Thanks again!

Pip