Hello,
I have a question regarding the offered cistern. Our development plan states the following:
The general contractor suggested that we install a cistern in the garden.
The current offer includes a cistern with a capacity of 4,000 liters (1,057 gallons).
The plot is approximately 540 m² (5,813 sq ft) in total. The house will be roughly 10 m x 11 m (33 ft x 36 ft), plus a double garage of 6 m x 6 m (20 ft x 20 ft), and a terrace...
Do you think this size is too small?
I have a question regarding the offered cistern. Our development plan states the following:
C 3. Water Management
C 3.1 The hardening of open areas should be limited to a minimum. Parking spaces and driveways should be paved with permeable surfaces (e.g., grass pavers, paving with grass joints, gravel turf, or similar).
C 3.2 The uncontaminated rainwater collected on private properties must be retained on the site and infiltrated or used as non-potable water.
Only wastewater must be directed to the sewage treatment plant.
C 3.3 A management concept must be developed and coordinated with SGD Süd, RS WAB, Neustadt for the disposal/use of rainwater that is not significantly polluted.
The general contractor suggested that we install a cistern in the garden.
The current offer includes a cistern with a capacity of 4,000 liters (1,057 gallons).
The plot is approximately 540 m² (5,813 sq ft) in total. The house will be roughly 10 m x 11 m (33 ft x 36 ft), plus a double garage of 6 m x 6 m (20 ft x 20 ft), and a terrace...
Do you think this size is too small?
This has become a common issue for municipalities (cities sometimes still manage it). The networks are overloaded, or there is a desire to develop new residential areas as cheaply as possible. Percolation or infiltration systems are then often required, usually with a reduction factor. This means that water is slowly discharged into the infiltration system. For the homeowner, this involves:
- A cistern
- A reduction area inside the cistern (usually 30%)
- An infiltration pit
Often, cisterns with 6000–10000 liters (1600–2600 gallons) capacity are installed (30% is not usable), along with a large infiltration pit. Using the working space of the cistern for infiltration is prohibited in most municipalities.
The problem is that although soil assessments are carried out beforehand, whether an entire residential area can handle this type of drainage is another matter.
On the other hand, I generally find cisterns very positive and would always install one in a new build. You always need water in the garden, as well as for washing your car and other tasks (although I’m not a fan of using it for the washing machine or toilet). We even retrofitted one last year in an existing property. It’s a plastic cistern, but the higher-quality ones have become very durable. Unfortunately, plastic is still significantly more expensive than concrete. Last May and June, I used over 18 cubic meters (635 cubic feet) just for the garden. After that, there was unfortunately no more watering needed. In a “normal” summer, that would be 30–40 cubic meters (1060–1410 cubic feet). You start to think whether to water for 5 more minutes or not. Additionally, our fresh and wastewater fees were increased by 20% from 2017 to 2018. It doesn’t matter at what interest rate I finance it. Environmentally, I think this makes a much bigger impact than most solar thermal or photovoltaic systems. For 40 cubic meters (1410 cubic feet) of garden watering, I wouldn’t worry about showering 2 minutes longer, even with a rain shower.
I admit, with a 1100 square meter (11840 square feet) lot, we do have a bit more space than average. Fortunately, a small stream runs behind our property. Our garage and cistern overflow drain into it. This saves me the cost of sealed surfaces, and in an emergency, I have the option to refill my cistern if needed.
- A cistern
- A reduction area inside the cistern (usually 30%)
- An infiltration pit
Often, cisterns with 6000–10000 liters (1600–2600 gallons) capacity are installed (30% is not usable), along with a large infiltration pit. Using the working space of the cistern for infiltration is prohibited in most municipalities.
The problem is that although soil assessments are carried out beforehand, whether an entire residential area can handle this type of drainage is another matter.
On the other hand, I generally find cisterns very positive and would always install one in a new build. You always need water in the garden, as well as for washing your car and other tasks (although I’m not a fan of using it for the washing machine or toilet). We even retrofitted one last year in an existing property. It’s a plastic cistern, but the higher-quality ones have become very durable. Unfortunately, plastic is still significantly more expensive than concrete. Last May and June, I used over 18 cubic meters (635 cubic feet) just for the garden. After that, there was unfortunately no more watering needed. In a “normal” summer, that would be 30–40 cubic meters (1060–1410 cubic feet). You start to think whether to water for 5 more minutes or not. Additionally, our fresh and wastewater fees were increased by 20% from 2017 to 2018. It doesn’t matter at what interest rate I finance it. Environmentally, I think this makes a much bigger impact than most solar thermal or photovoltaic systems. For 40 cubic meters (1410 cubic feet) of garden watering, I wouldn’t worry about showering 2 minutes longer, even with a rain shower.
I admit, with a 1100 square meter (11840 square feet) lot, we do have a bit more space than average. Fortunately, a small stream runs behind our property. Our garage and cistern overflow drain into it. This saves me the cost of sealed surfaces, and in an emergency, I have the option to refill my cistern if needed.
There are significantly more affordable infiltration systems than the one previously described. A cistern is also not necessary, as they are usually extremely uneconomical. For example, those mentioned 40m³ (52.3 yd³) of water cost less than €70. You can water for decades before you recover the initial investment. Moreover, the cistern often has little water exactly when you need it. To avoid this, cisterns have to be quite large, which makes the investment more expensive again.
I am now paying almost €90 for 40m³ (52yd³). If I compare that to €1500 for a monolithic concrete cistern, it will eventually pay off. However, my main reason for getting it was so I can water properly in the evenings without feeling guilty.
A cistern is definitely not a solution for infiltration or drainage.
A cistern is definitely not a solution for infiltration or drainage.
Sure, if you are required to install a cistern anyway, it would be unwise to save the last 200€ on the pump. But I wouldn’t do it voluntarily. It’s not worth it if you can exempt the outdoor faucet from sewage charges by using a separate meter. Then you only pay for fresh water, which is quite affordable.
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