Extra Water Harvesting

With reduced rainfall in the last 12 months we have been low on water since the start of 2023. The extra water tanks on the land have kept us in water but they were designed to give us extra water to keep the plants growing season going through the hot summer. So, we started a new project to see of we can increase the flow off our natural sloping rocks. The rain will normalise back but autumn 2022 and spring 2023 did not produce the normal heavy rainfall so for now we are short. To be clear there is no climate emergency causing this LOL.

To clarify our situation note that our house cisterna holds around 40,000L and on average over the last 6 years we have been 59% full at the end of July, and never lower than 40% full. This year we are at 31% full at the end of July and through the year we have been no higher than 42%. This means that the gap in water is lower than it was in April where we are normally at 100% full and this year we were only at 40%, so a gap of 60%. The current gap of 28% is equal to 11,000L and represents 10 weeks of our consumption. With the summer rain showers we have had so far and the 3 months of water we already have we will last until the autumn rains. To extend that further and to accommodate visitors extra consumption we are using a launderette for the laundry and 8L bottled water which we then filter for drinking.

Meanwhile the 15 garden water tanks are less impacted due to their average capacity of 750L but we want to expand our food growing to increase our self sufficiency and protect against differing weather patterns. So, the idea is to increase the water flow off a rocky area that already feeds fills one 500L tank three times a year. The 1st picture below shows the area of rock to be cleared and the 2nd photo shows the two 500L tanks that ideally are filled. The third picture shows how the water gathers in the rock after some clearance and makes its way over the edge into the tanks. 

The results so far have created a learning without any significant extra water. While a large storm is needed to really prove the concept and more clearance work is needed further up the rocky area to prevent water capture by plants and soil. The rocks are quite porous like a limestone so some water does not get to the rock edge before it disappears. Our land appears to have natural rock flows that will help water harvesting and also signs that in the past previous owners had moved rocks to increase the level of water harvested.