Is it worth collecting rain water from a polytunnel?

Lots of people raise the question about whether its worth collecting rain water from a polytunnel and its fair to say that there is lots of methods tried, mostly unsuccessful. We actually try and dissuade our customers form bothering as the extra expense of installing a system for successful water collection is often not worth the cost compared to mains water.

However, the trend, especially in Wales with One Planet Development, is that people are erecting tunnels on sites without mains water and  therefore collecting the rain water from the polytunnel is essential.

The main problem is that you need sufficient storage for the water at times when its raining. An IBC ( international bulk container) can be placed at the collection point, but at wet times of the year you need to be able to have several to fill, and devise a method of either moving the full ones or linking them so they all fill. One IBC full of water will only last a couple of days in a large tunnel.

The next problem is how to achieve it.

You can purchase stick on gutter, but in truth you are sticking this to a flexible surface that is exposed to the weather and it has the potential to fail after a couple of seasons

You can attempt to stick a strip of polythene along the length of the tunnel and hang this over into a gutter, but again the tape fails after a season or two.

At Five Star Polytunnels , one of the installers that we recommend has devised a successful method of introducing a guttering  system down the length of the tunnel, but at quite a cost.  An addition side rail needs installing, and the main cover is fitted to this. A base rail is still needed so the gap between the rails can be infilled, this can be with net or polythene.  This method is successful and long lasting but whether it is actually worth it is a difficult question to answer.