Frequently Asked Questions

What is the situation regarding hygiene of rainwater for toilet flushing and washing machines?

Studies have shown that the average counts of bacteria found in rainwater are far below the recommended values for bathing water or food (e.g. salads). In fact, bacteria play no role in the use of rainwater for toilet flushing, because their counts in comparison to the main germ carriers of human faeces are negligible. The same is true for laundry. Comparison of the bacteria counts of rainwater results in the same ratio.

Concrete Cistern or Plastic Tank – Which is better?

Unlike concrete cisterns, plastic tanks can in most cases be moved without heavy equipment owing to their lower weight and can thus avoid greater damage in the pit and in the garden. This is particularly important if you install a rainwater utilization system in your garden afterwards. Another advantage of the plastic tank is the more comfortable cleaning, because concrete tanks have rough inner walls where dirt can get stuck easily. There is also a risk of contamination of the rainwater due to leaching cement particles, which in the worst case can cause damage to the pump. Moreover, calcium carbonate (lime scale) precipitations from the concrete of the cistern or tank can make the originally lime-poor rainwater “hard” and can thus shorten the life of your washing machine.

How often should the tank be cleaned?

Depending on the pre-cleaning (filter) of the rainwater, the tank has to be cleaned every 8 to 10 years at the earliest. Non-filtered floating fine particles enter the tank, fall to the ground and form a sedimentation layer, which has even a positive effect on the water quality (see next point). Therefore, cleaning has to be made only after a larger sediment layer thickness has built up.

What is sedimentation and how does it work?

Sedimentation cleans the water which has been collected and is therefore as important as the filtration process upstream of the tank is. Non-filtered floating fine particles enter the tank and sink down to the tank ground due to their own weight. Dissolved substances are taken up by the sinking floating particles (adsorption), which are in this way also removed from the water and then deposited in the sediment. This results in clear water of high quality above the sediment. It has to be noted well, however, that any stirring up of the sediment layer is prevented due to a calmed inlet.

How much can I save and what about profitability?

You can save up to 50% of your daily drinking water consumption using a Rainwater Utilisation System. This can be a quantity of up to 70 litres for one person every day (if the rainwater is used for toilet flushing, the washing machine, garden irrigation and car wash). Thinking of the increasingly elaborate and expensive treatment of drinking water, the projected doubling of drinking water prices in the coming years is only a logical consequence. Therefore, a Rainwater Utilisation System makes sense in two respects: It will not only relieve and protect our environment, but also your finances in the long term.

What legal rules have to be observed in a Rainwater Utilisation System fitted with a back supply?

· Strict separation of drinking water and rainwater.
The DIN 1988 standard allows protection of the drinking water against contamination.
This means that the free outlet has to be used for the supply of drinking water into Rain Water Utilisation Systems.
Of course, all series of Speidel Drinking Water Back Supply Units are equipped with a “free fall”.

· Identification of the piping and tapping points
The tapping points have to be identified in a way that it might be recognized at any time which tapping points and piping carry rainwater.
We offer a special labelling kit for this purpose.

Are public subsidies granted for Rainwater Utilisation Systems?

Meanwhile, the installation of systems for rainwater utilisation is encouraged by some municipalities directly or indirectly as a step forward to active ground water protection. Pertinent information on funding possibilities on site may be obtained from the construction and environmental agencies of your municipality.