Rainwater use

Regarding yesterday’s letter on rainwater storage, many years ago Auckland suffered an extreme drought. The local dams supplying water nearly dried up so there were incentives for residents to install water tanks to store rainwater. Emergency supplies of water were also piped up from the Waikato River to help out.

This was made permanent and a big percentage of Auckland Super City water comes from this source.

Going back to my early childhood (I’m now 83), only large towns and cities had municipal water, the rest of New Zealand used tanks storing rainwater.

Later, major Auckland drought regulations were brought in that said you could only use stored rainwater for washing machines and to flush toilets! You were not allowed to use household water, as well anti-backflow valves had to be installed to stop rainwater flowing back into the mains.

A big feature of rainwater was that it was a soft water. A point to remember if using rainwater exclusively is that it is slightly acidic where as town supply water is alkaline, all copper pipe is treated to stop alkaline water attacking that copper pipe. Rainwater will attack that copper pipe, so the solution is to put a couple of concrete building blocks in the water tank to turn the water acidic to stop that problem. There was no problem years ago as galvanised pipes were used.

Eric Strickett, Massey.