Water Tanks South Christchurch and Port Hills

Rainwater tanks on the Port Hills and Banks Peninsula

South Christchurch and the Port Hills include some of the region's most varied water arrangements. Hill suburbs such as Cashmere are fed from reservoirs or tanks on the council network, while on Banks Peninsula, Birdlings Flat, Little River, Pigeon Bay and Wainui are restricted supplies where each property needs its own storage tank and use is limited to 1,000 litres a day. For those homes a tank is essential, not optional.

On steep sections, placing a tank is the main challenge. A full tank is very heavy, so it needs a level, stable base, and on the hills that often means a cut platform or engineered pad away from unstable banks. Cashmere and Lyttelton had rockfall and landslips in 2010 and 2011, and we avoid siting tanks below or above unstable ground. Getting the tank to the site may also take extra planning on narrow paths.

In Halswell, Spreydon and Beckenham, flat sections and good roof areas make garden tanks simple. Halswell's new subdivisions are a good place to install a tank as the house goes up, with the base and pump power planned in from the start.

If tank water is used for drinking, we fit filtration and UV treatment, because keeping private tank water safe is the owner's responsibility. We fit leaf screens and first flush diverters, and on hillside homes with trees nearby, extra gutter guards help keep leaves out. Pumps are sized for the height difference between the tank and the house, because pushing water uphill needs more pressure.

For Lyttelton homes on the crater rim, the harbour wind and salt air mean we choose pumps and fittings that resist corrosion, and we secure the tank against the gusts that funnel through the hills. Hoon Hay's semi rural edge has bigger sections where larger tanks fit easily.

Local tip: On a Port Hills section, check the ground stability and access before choosing a tank size, because a large tank needs a large, stable platform.