Additional to Rainwater System in Issue 2Reader submitted

Having installed a rainwater system a couple of years ago, I would like to share my experience. Firstly, my experience of the rainwater diverters shown in your article is that they block with leaves. Unless you have almost no leaves falling in your guttering, I think the 12mm connection shown in your illustration will quickly block and require the fittings to be taken apart and cleaned, even with the gutter witch. Leaves break down in the gutter. A better solution is a Marley Leaf Slide (see photo), which allows full flow of water. Use 80mm downpipe and droppers to allow leaves to pass.  The wire screen still requires periodic cleaning but this is much easier.

Secondly, a reality check.  It is unlikely that your water will be either cheaper or use less natural resources than council water, taking into account initial setup and likely life, but you can reduce the need for new council dams.  Other positives are better flow to your garden hose if you use an electric pump (council meters usually reduce flow dramatically though the static pressure in the pipe may be high); and chlorine free water which is better for your garden and preferred by birds if you have a bird bath.

Start by estimating how much water you need for this to be a useful project. You can estimate garden consumption by timing how long it takes to fill a 10 litre bucket and how long it takes to water your garden.  Divide the hose time by the bucket time and multiply by 10 to get the litres per watering. You can use the same method with your washing machine as it pumps out if you want to supply that. Then calculate consumption for a month.  In Auckland this is a reasonable minimum stretch.  You might also like to check out the money side of it, in Auckland council water costs $1.30 per 1000 litres, but if you also take into account the waste water charge which is based on fresh water consumption the cost is about $3 per 1000 litres.  When I installed my tank a permit was not required for a 10,000 litre tank, the only restriction was a boundary shading limit for tall tanks. The council was happy for me to supply my washing machine without charging extra for waste water, presumably this will continue. Council seemed mainly concerned that if I sold my house and the next owner was not interested in my water works, everything would still function.

I’m happy with what I did now that it’s done but I’m not sure I’d do it again. I have two tanks, 1,600 litre and 10,000 litre. 260kg of plastic was used to make the tanks. The small tank is a holding tank which collects from the roof, I use a small pump to fill the large tank from that. There is a pressure pump which supplies the garden and washing machine and washing the car. During winter the small tank is all I need most of the time. There is a filter (fine plastic gauze) on the pressure pump, that’s enough. I’ve catchment from a double garage and half the house roof but the garage roof would probably be sufficient. If you buy a pressure pump there are two things you should ask, if the water runs out will the pump turn itself off or will it destroy itself. Does the pump need maintenance (mine has a rubber bladder which needs to be pumped up with air periodically).