Warrandyte- water saving garden

This very large garden [5 acres?] has an involved system of water tanks to collect rain from the house and shed roofs and saves all of it for watering the garden, and filling a huge concrete tank at top of block that is used by country firefighters, to fighting bushfires. Pumps are used to move water from the lower tanks to the upper tanks. Originally when they first went to live here 1970, it was dry bush, so hey took water from the Yarra river but now they do not have to. We had a detailed lecture on how the watering system worked. However they rely on normal reticulated town water for household purposes.

How to measure water level in concrete tank. One longtube [3 times the height of tank ] in tank and out with dye in water to show the level in the tank