The hosts for this project had spent a year in Australia where they saw the prolific use of rainwater tanks. They were interested in adding a tank to their recently remodeled landscape and had only a narrow strip next to the house where one would fit. Slimline tanks are made for just such purposes. After a bit of researching and measuring, our hosts decided to put in two Slimlines, one that holds 530 gallons and another that holds 265 gallons.
The tanks fit next to the wall a ways from the downspout so we designed a wet system to get the water into the tanks. Eight volunteers separated in two crews put the piping and fittings together and dug the basin for the overflow.