Rain Harvesting

It has taken three and a half weeks and the tail end of yet another tropical cyclone, the third this year, to fill our tanks from empty, or so we hope. 

Since completing the installation of our rain harvesting and water storage system on the 20th of April, during our Easter visit, we have been monitoring the daily rainfall at Tolaga Bay through the Metservice website.

​You can read about the details of our rain harvesting system on our Water page.

After a showery end to April, Tolaga Bay recorded nearly 5mm of rain on the 30th followed by nearly 28mm of rain on the 1st of May. All going well, and allowing for losses through the first flush diverter, these two rain events should have delivered 800 litres of water into our tanks. 

However it is doubtful the rainfall intensity would have been enough to get water into the potable water tank.

Cyclone Donna at the height of its fury.

​The following 10 days were devoid of any heavy rain before the arrival of Cyclone Donna, which began life near Vanuatu and became a Category 5 storm and the most powerful tropical cyclone ever recorded in the Southern Hemisphere in May with winds approaching 300 km/hr at their peak.

Its path southwards past New Zealand, thankfully downgraded to a Tropical Low, once again drenched the east coast of the country and Tolaga Bay recorded over 73mm of rain on the 12th and 13th of May.

This level of rainfall should have yielded a further 1,800 litres of water to completely fill our tanks. Rainfall intensities during the storm easily exceeded 5mm/hr meaning water would have begun filling our potable water tank. We need less than 25mm of rain in excess of 5mm/hr to totally fill our supply of drinking water.

Theory is one thing, practice is another and we will not know for sure how our rain harvesting system has performed until we next visit Tane's Rest. We could have been defeated by wind blown debris clogging the guttering to stop water getting to the tanks, or our tanks may indeed have filled but will be empty by the time we return if I did not sufficiently tighten a fitting, or worse still cracked a pipe while installing it.

​Without water available when we installed the system we could not test it so our bounty of harvested water may be being lost drip by drip as I write this post.

Maybe we will take water with us on our next trip, just in case.