ᐅ Annual Garden Water Demand – Is a Rainwater Harvesting System Worth It?
Created on: 18 May 2020 13:41
B
Brainstorming
Hello everyone,
I am currently trying to estimate whether installing a rainwater cistern is worthwhile for our new build. We will have about 100 sqm (1,076 sq ft) of garden/lawn to plant. According to various online cistern calculators, I need roughly 8,000 to 11,000 liters (2,113 to 2,906 gallons) of water per year for this area in our region, which receives about 550 mm/sqm (22 inches/sq ft) of rainfall. The price for water and wastewater is approximately 2 euros per cubic meter. Based on this calculation, the cost for garden irrigation without a cistern would be around 22 euros per year.
If I now install a cistern with a capacity of 1,000 liters (264 gallons), I expect costs for the cistern, pump, and roof drainage connection to be between 1,000 and 1,500 euros. Assuming a budget of 1,000 euros, it would theoretically take more than 45 years for the cistern to pay for itself (without considering rising prices or repairs).
Am I missing something here? Could you possibly share your garden water consumption? Maybe the online calculators don’t match real-life usage.
Thanks
I am currently trying to estimate whether installing a rainwater cistern is worthwhile for our new build. We will have about 100 sqm (1,076 sq ft) of garden/lawn to plant. According to various online cistern calculators, I need roughly 8,000 to 11,000 liters (2,113 to 2,906 gallons) of water per year for this area in our region, which receives about 550 mm/sqm (22 inches/sq ft) of rainfall. The price for water and wastewater is approximately 2 euros per cubic meter. Based on this calculation, the cost for garden irrigation without a cistern would be around 22 euros per year.
If I now install a cistern with a capacity of 1,000 liters (264 gallons), I expect costs for the cistern, pump, and roof drainage connection to be between 1,000 and 1,500 euros. Assuming a budget of 1,000 euros, it would theoretically take more than 45 years for the cistern to pay for itself (without considering rising prices or repairs).
Am I missing something here? Could you possibly share your garden water consumption? Maybe the online calculators don’t match real-life usage.
Thanks
There are types of grass that don’t develop deep roots. Even deep-rooted grass looks burned after 3-4 weeks of drought and heat. It’s also a matter of expectations. If I invest a lot of money and personal effort in the outdoor area, I want to maintain it and keep it looking good.
If I have free rainwater for that, it’s no problem.
It’s nothing more than a hobby.
And 1,000 liters (264 gallons) is nothing. Some newly planted trees need that amount in just 2 weeks.
For example, we installed a 76,000-liter (20,000-gallon) cistern...
For most gardens, around 7-8 m3 (7,000-8,500 gallons) is probably the most practical size.
If I have free rainwater for that, it’s no problem.
It’s nothing more than a hobby.
And 1,000 liters (264 gallons) is nothing. Some newly planted trees need that amount in just 2 weeks.
For example, we installed a 76,000-liter (20,000-gallon) cistern...
For most gardens, around 7-8 m3 (7,000-8,500 gallons) is probably the most practical size.
We have already discussed the garden water demand... I think 20 liters per square meter (0.65 gallons per square foot) is hugely exaggerated. Especially since part of it is supplied by rainfall, meaning it is not a suitable planning figure for consumption forecasting. Irrigation systems in hedges, etc., are regularly unnecessary; they only spoil the plants. The establishment phase is, of course, important, as is the case with a new tree, but permanent irrigation is, in my opinion, the wrong approach.
20 liters per square meter (0.2 inches per square foot) includes precipitation for a shallow-rooted lawn with optimal care. 10–20 liters (0.1–0.2 inches) are usually sufficient.
Most people won’t even fertilize their lawn...
As @guckuck2 wrote, plants shouldn’t be pampered too much. Only then will their roots grow deeper and they become more resilient to dry periods.
Since we will probably experience more dry spells, I would plan accordingly. I don’t want to sit on my terrace while all the plants in the garden suffer or die...
I don’t see the point in using fresh water, and it also costs accordingly.
Most people won’t even fertilize their lawn...
As @guckuck2 wrote, plants shouldn’t be pampered too much. Only then will their roots grow deeper and they become more resilient to dry periods.
Since we will probably experience more dry spells, I would plan accordingly. I don’t want to sit on my terrace while all the plants in the garden suffer or die...
I don’t see the point in using fresh water, and it also costs accordingly.
A
AleXSR70020 May 2020 08:57@rick2018 :
76,000 liters (20,043 gallons)? Or 7,600 liters (2,007 gallons)?
76,000 liters (20,043 gallons)? Or 7,600 liters (2,007 gallons)?
Hello,
Neither, but it really depends on the location. In the North German Plain, irrigation is a different matter than here. We live in Franconia, one of the drier regions in Germany. Every year, we use about 150 cubic meters (5300 cubic feet) of water to irrigate roughly 350m² (3800 sq ft) of garden. Irrigation has been running since early April! Cisterns are completely useless here; some neighbors have them, but they are usually empty by April and stay that way until late summer.
We pay 2 euros per cubic meter for our garden water, so about 300 euros per year. For a large cistern, including installation and equipment, you quickly reach 5000 euros or more.
And with a cistern, you still have to install filters and change them regularly to prevent suspended solids from clogging your sprinklers.
So it’s not really worthwhile. Most neighbors also clearly say they wouldn’t do it again.
Best regards,
Andreas
Specki schrieb:
Tell me, do you all really need golf-course-quality lawns in your gardens, or do you have 4000m² (43000 sq ft) plots?
Neither, but it really depends on the location. In the North German Plain, irrigation is a different matter than here. We live in Franconia, one of the drier regions in Germany. Every year, we use about 150 cubic meters (5300 cubic feet) of water to irrigate roughly 350m² (3800 sq ft) of garden. Irrigation has been running since early April! Cisterns are completely useless here; some neighbors have them, but they are usually empty by April and stay that way until late summer.
We pay 2 euros per cubic meter for our garden water, so about 300 euros per year. For a large cistern, including installation and equipment, you quickly reach 5000 euros or more.
And with a cistern, you still have to install filters and change them regularly to prevent suspended solids from clogging your sprinklers.
So it’s not really worthwhile. Most neighbors also clearly say they wouldn’t do it again.
Best regards,
Andreas
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