- Rainwater: for what purpose?
- Choose the right tank dimension
- Think about the water of the well
Watering a garden is expensive and uses a lot of drinking water. To save our environment and save money, think of rainwater.
• To collect rainwater, simply channel the water from the gutters of your roof and store it in a tank. This can be aerial (garden, basement, garage, etc.) or buried.
• When the tank is full, an overflow directs the excess to the sewer. When the tank is empty, the water network takes over.
• It will be necessary to install a pump if the tank is placed lower than the garden (buried or in a cellar) or if one needs a big pressure (2/3 bars). Otherwise, the weight of the water will be enough to create the pressure. But beware: it can be just enough if you have big needs.
Rainwater: for what purpose?
In addition to watering, this water can be used inside the house for washing the floor or removing toilets.
• Exceptionally (a declaration in town hall is mandatory), it can be used to power the washing machine. But it must then be disinfected and maintain a maintenance record of the tank.
• In any case, you should not drink it and it is not advisable to use it (like our German neighbors) to fill the pools.
Choose the right tank dimension
What capacity is needed? To estimate the amount of water recovered and choose the right tank, a small calculation is enough...
We must know how much water is available to him. This is the local precipitation (A) measured in l / m2 / yr or mm / yr (1 l / m2 = 1 mm).
By multiplying this figure by the roof area (B) and a loss coefficient of 0.9, the amount of recoverable water is obtained:
A x B x loss coefficient 0.9 = P (in liters / year)
We must then estimate its needs (C). For example, a garden requires 60 l / m² / year, a toilet 8,800 l / year, a washing machine 3,700 l / year, etc.
What size of tank?
Finally, calculate the average between your potential and your consumption [(P + C / 2) x (21/365)].
In general, a tank providing a reserve of three weeks of water is sufficient. But depending on the region, one can experience longer dry seasons during which one can only rely on his reserve. It is then necessary to modify the calculation.
Think about the water of the well
The owner of a lot also owns the basement. This means that if a source or groundwater flows under its ownership, we can capture the water and use it as we see fit. It is rare that it is drinkable.
But, after analysis, the DDASS can confirm its potability. Whatever the result of the tests, it can be used to water the garden and feed the flushes. Just dig a well and plunge a pump into it (quieter than an overhead pump).