Rainwater harvesting – relief in times of drought |18 October 2010

It’s October now – usually a month when the south-east monsoon dies down and we start getting a little more rainfall. But the Met Office predicted a drier September and October than normal, and their predictions seem to have come true. 

While we cannot say that the abnormally dry weather at present is caused by climate change, there have been so many anomalies in weather patterns over the last decade or so that it really makes you wonder.

The funny thing is that we get so much rain in Seychelles – a little over two metres of rain falls every year over the main granitic islands. Technically, this should be more than enough to supply us with all the water we need for our homes, and even hotels and other industries.

The trouble is, how do we store all this rainwater to use in times of drought? The PUC has a very, very limited reservoir capacity, as we all experience daily. In recent years, our solution has been desalination, but the desalination process uses a lot of energy (so contributes to climate change) and is thus very expensive. Consumers are also very often dissatisfied with the end product.
So where do we go from here?

We could build new reservoirs, but that is tricky. We don’t have a lot of space and, of course, we don’t want to damage habitats up in the mountains either. The PUC is exploring possibilities for new small or medium-sized reservoirs by undertaking a hydrogeological study of Mahe, Praslin and La Digue.

Early findings suggest that we could, at fairly low cost and minimal impact to the environment, build a medium-sized reservoir at Mare Aux Cochons that would alleviate a lot of our problems.   Other small reservoirs could be built on some of the larger rivers that don’t dry up during times of drought.

These are options for the PUC and the government to pursue, but there are also options for us at home. 
First of all, everyone needs to have a storage tank for PUC water, so that when the water goes off, something still comes out of our taps. Secondly, everyone should be harvesting rainwater at home.

Your system can be as basic and simple as an open barrel well placed where the rainwater drains off a roof. It’s a good idea to keep your barrel covered when it’s full to stop mosquitoes breeding in it.

If you have gutters along your roof and want to go a little more high-tech, you can connect your roof to a downpipe leading straight into a covered tank with a tap installed somewhere down near the bottom.

More high-tech options include pumping rainwater up to a tank in the attic or somewhere else high enough to provide good water pressure. If you are still building your house, you could incorporate an underground cistern to store rainwater as they do in Bermuda.

Plumbing fixtures for rainwater harvesting are not complicated and are usually available at hardware supply stores. You can buy used barrels from Trois Frères Distillery, Indian Ocean Tuna and Penlac, or get a new (but more expensive) fibreglass or plastic one. You can also, of course, build one out of cement blocks.

Rainwater can be used for all purposes not requiring PUC treated water – showers, toilets, gardening, washing clothes, the car, the house etc. Remember, though, that you should use treated water (even filtered, boiled rainwater is fine) for cooking and drinking.

Rainwater harvesting systems can be installed wherever there is a roof, so owners of small buildings, flats, businesses – or government offices, farmers etc – can put them to good use as well. 

Many schools are installing systems as part of a Ministry of Education project, and these will hopefully inspire more community members to follow suit and set up a system now to be ready for the next dry season.

Contributed by Sustainability for Seychelles. For more information, contact them at info@s4s.sc  or tel: 717833.