Good day!
The ongoing dry spell has brought up a topic again that I have postponed several times: Where should the water for garden irrigation come from? Until now, I have been using water from the public supply: always available, consistently good pressure, and fairly cost-effective thanks to separate metering. But it probably isn’t sensible to let high-quality drinking water soak into the garden soil.
Is there a general rule of thumb about which form of garden irrigation is best from both financial and ecological perspectives? Essentially, there are three options: water from the public supply, collecting rainwater from roofs in cisterns, or drilling a well (if permitted).
To make the use of rainwater worthwhile, you would need to store a large volume, at least 20 to 30 cubic meters (700 to 1,060 cubic feet) to cover dry periods. The costs for cisterns and the associated earthworks would accordingly be high. Then there are ongoing expenses, such as electricity and maintenance for the pump. Drilling a well also involves costs, plus electricity and pump maintenance. The advantage of a well is that you don’t have to worry about storage capacity.
My garden irrigation system (drip hoses under mulch) consists of four zones, each of which requires one cubic meter (35 cubic feet) per hour. During prolonged dryness, I would ideally run each zone for one hour every two to three days. That adds up to about ten cubic meters (350 cubic feet) per week. With 30 cubic meters (1,060 cubic feet) of storage, this would last just about three weeks. We are increasingly facing situations in Berlin where it doesn’t rain for well over three weeks.
Has anyone here already worked through this in detail?
Matthias
The ongoing dry spell has brought up a topic again that I have postponed several times: Where should the water for garden irrigation come from? Until now, I have been using water from the public supply: always available, consistently good pressure, and fairly cost-effective thanks to separate metering. But it probably isn’t sensible to let high-quality drinking water soak into the garden soil.
Is there a general rule of thumb about which form of garden irrigation is best from both financial and ecological perspectives? Essentially, there are three options: water from the public supply, collecting rainwater from roofs in cisterns, or drilling a well (if permitted).
To make the use of rainwater worthwhile, you would need to store a large volume, at least 20 to 30 cubic meters (700 to 1,060 cubic feet) to cover dry periods. The costs for cisterns and the associated earthworks would accordingly be high. Then there are ongoing expenses, such as electricity and maintenance for the pump. Drilling a well also involves costs, plus electricity and pump maintenance. The advantage of a well is that you don’t have to worry about storage capacity.
My garden irrigation system (drip hoses under mulch) consists of four zones, each of which requires one cubic meter (35 cubic feet) per hour. During prolonged dryness, I would ideally run each zone for one hour every two to three days. That adds up to about ten cubic meters (350 cubic feet) per week. With 30 cubic meters (1,060 cubic feet) of storage, this would last just about three weeks. We are increasingly facing situations in Berlin where it doesn’t rain for well over three weeks.
Has anyone here already worked through this in detail?
Matthias
S
Steffen809 Apr 2020 12:51Despite having a good pump, we only have 6 sprinklers arranged in a circle, and that works well. I tested the pipeline once... it maxed out at 3. For a lawn area of about 600 square meters (6500 square feet), the watering shouldn’t take half the day.
Irrigation can be effectively spread over several nights or mornings. In summer, 2–3 cycles per week are usually appropriate. Drip irrigation can also run during the day. There are significant differences between sprinklers in terms of range, angle, precipitation rate per m2, water consumption, and so on. This also influences how long irrigation needs to run. Together with the piping and water supply, this determines the number of sprinklers per zone. However, this varies from zone to zone. A 360° sprinkler uses four times as much water as a 90° sprinkler of the same design. Therefore, recommendations about how many sprinklers to have per zone or what is feasible don’t make much sense.
@Steffen80 focuses on the flow rate rather than the pressure for the water connection.
Many people underestimate water requirements. Manual irrigation is not comparable. Lawns need about 20 liters per m2 per week in summer. For Steffen, this would already mean 48 m3 of water per month (without natural rainfall). This shows that having a well is very useful. Despite the electricity costs for the pump, it pays off quickly. A cistern is also a good solution to collect rainwater. Its size must be adapted to the roof area and natural rainfall. A combination of a well and a cistern is the best (and most complex) solution. Supplying water from the mains is the worst option due to flow restrictions, costs, and ethical considerations.
@Steffen80 focuses on the flow rate rather than the pressure for the water connection.
Many people underestimate water requirements. Manual irrigation is not comparable. Lawns need about 20 liters per m2 per week in summer. For Steffen, this would already mean 48 m3 of water per month (without natural rainfall). This shows that having a well is very useful. Despite the electricity costs for the pump, it pays off quickly. A cistern is also a good solution to collect rainwater. Its size must be adapted to the roof area and natural rainfall. A combination of a well and a cistern is the best (and most complex) solution. Supplying water from the mains is the worst option due to flow restrictions, costs, and ethical considerations.
S
Steffen8010 Apr 2020 09:23We have a 15m³ (530ft³) cistern, but unfortunately, a well is not an option for us. The cistern was always empty last year. Our garden water consumption was 240m³ (8,478ft³).
Steffen80 schrieb:
We have a 15m3 (530 ft3) cistern, but unfortunately we can’t have a well... The cistern was empty all last year. See, that’s exactly what I feared. You spend a lot of money on cisterns and excavation to store a certain amount of rainwater, and even then, you often reach a point where it’s not enough. So maybe it’s better to have just a small rainwater tank to supply the few plants that absolutely mustn’t get any lime, and cover the rest with well water if possible... That’s my conclusion for now.
Alternatively, install a large cistern. With a well, you can continuously refill it and store water. You can also collect rainwater during periods when irrigation is not needed... The additional cost between installing 15 or 30m3 (530 or 1,060 cubic feet) is not that significant anymore. About four weeks of self-sufficiency for garden water supply is quite good.
S
Steffen8010 Apr 2020 14:40rick2018 schrieb:
Or install a large cistern. With a well, you can continuously refill it and store water. You can also collect rainwater during periods when watering isn’t needed...
The additional cost of installing 15 or 30m3 (530 or 1,060 cubic feet) isn’t that much different.
About 4 weeks of self-sufficiency for garden water supply is quite good. although 30m3 (1,060 cubic feet) isn’t that much either
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