Rainwater "a gift from heaven" RE-imagined

Save up to 100% drinking water

Particularly in countries with a centralized water supply, rainwater is hardly used except for flushing toilets and garden irrigation. In many areas however, sufficient rainwater of excellent quality is available to cover almost the total water requirement.­­­­­­­­­­­­­­­­­­­­­­ With technology from INTEWA, this is now possible.

Showering - drinking - washing - garden

Now every­thing is pos­si­ble. Use your house as your own water sup­ply by col­lect­ing rain­fall, as a gift from heaven, in drums. Treat it with the AQULOOP tech­nol­ogy and thus have an al­most self-suf­fi­cient water sup­ply.

Back to the "Water Future"

Water comes from the faucet, to modern people this is self-evident. But this will continue forever because problems are increasing. It is worth taking a look into the past.

Stone Age

Early peoples drank natural surface water, whose origin was rainwater.

Medieval - Modern Times

As people settled down, the settled on the water. Next came diseases caused by germs, as well as bottlenecks in the supply.


Today's contaminants, such as trace elements from medicine and agriculture, cannot be removed from the water by modern systems. However, membrane filtration anddigital monitoring systems alreadyable the use of small, decentralized systems. With this technology, a rethink is possible.


The vision is, at least in areas of sufficient rainfall, decentralized, pure rainwater is collected from every house and processed directly on-the-spot to drinking water.

Advantages of rainwater

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Animals love limes-free water

Almost everyone who owns a pet, which is allowed to go out from time to time, knows this. If you have the­ choice between ­rainwater ­and tap ­water ­then ­of course ­rainwater is the preferred choice­­­­­­­. Dogs and cats­ have very sensitive noses. Bacteria­­­ are­ neutralised by stomach acids­­­­­­. The composition­­­­ of water content influences taste­­­­­­­. Dogs and cats ­also do not much like the chlorine ­­taste, as well as hard­ water­­.


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Lime-free rainwater increases the life expectancy of water hot systems

The ri­sk­ of limescale deposits increases with rising water temperatures­­­­­ ­­­. Limescale initially deposits at places with the highest temperature, so at surfaces that transfer heat­­­­­­­­­­­­. The consequences of the deposits­­­­­­:

  • The system requires more energy to heat the water, because the limescale acts as an insulating blanket.
  • It not only deteriorates heat transfer, the pressure also drastically decreases due to the rough walls and the reduced flow cross section.



Frequent descaling of coffee machines, kettles and so on no longer has to be done and limescale deposits no longer happen in your pipes­­­­­­­­­­­­­­­­­.

Various studies have shown a savings potential in houses using soft water­­­­­­­­­­­­­­­. An overview is given from a study by the Karlsruhe Energy Centre (TZW) and the Institute for Systems Technology and Innovation Research (Frauenhofer ISI). ­­­­­­­­­­­­­­­­­­­­­­­­­With a reduction in water hardness from level 4 to level 2 up to €1.44 per m³ can be saved for decommissioning a household descaling system ­­­­­­­­­­­­­­­­­­­­­.

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Tea and coffee taste better with soft water

Do you like to drink a good cup of tea?­­ Then soft water is exactly right for you!­­­ True tea lovers have known this for a long time: soft water is indispensable for a rich taste experience­­­­­­­­­­­­­­­. Even the old venerable English Royal Society of Chemistry mentioned in their study that soft water is necessary in the preparation of a perfect cup of tea.­­­­­­­­­­­­­­­­­­­­­­­­ And also coffee fans have learned the value of soft water to optimally release aromas­­­­­­­­­­­­.

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No need to buy bottles of drinking water

In many countries on earth, the quality of tap water is so poor that it is not of drinkable quality without further preparation­­­­­­­­­­­­­­­­. In Germany, drinking water is one of the most controlled foods.­­­­­­­­­­ But why even here is­ drinking­ water­ often not drunk from the tap but­ instead­ a lot of money is spent to purchase bottled water­­­­­­?


Only a few years ago mi­ne­ral ­wat­er not only had to be­­­­ of "original purity­­­­" and could not be changed, but also had to be rich in minerals.­­­­­­­­­­­ This last passage has tipped the EU legislation. Mi­ne­ral­ water ­is differentiated from source water. Source­ water is water from subterranean sources, but it can have impurities.­­­­­­­­­­­­ It must meet the criteria for drinking water.­­­­­­­ Ta­ble ­water­ is bottled water­ (may also be tap water­­­), it can - unlike source and mi­ne­ral­ water­ - be mixed with salts­­­. In particular supraregional trade markets are relatively poor in minerals. ­­­­­­­­­­­­­­­­­­

Measured on daily requirements, one should drink more than 8 l of water to meet the requirements of calcium, and for magnesium the situation looks even worse.­­­­­­­­­­­­­­­­­­Therefore, one may just as well drink tap water­­­­­­. Important­:  the requirements of minerals are however mainly covered by solid food­­­­­­­­­. As the main task of water in the body is to be a transport medium and not a supplier of minerals, it is advantageous to use pure water, such as rainwater­­­­­­­­­­­­­­­­­­­­­­­­.


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No more annoying limescale deposits on faucets, less cleaning

Hard, limescale-containing water causes limescale deposits on water taps, shower cabins, ceramics and stainless steel sinks.­­­­­­­­­­­ ­­­­­­­­­­­Dry rubbing and daily cleaning is no longer needed and chemical cleaning materials can stay in the cupboard­­­­­­­­­­­­­­­­­­.

Let rainwater clean your bathroom and kitchen!­­­­­


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Maintenance cost-savings with lime-free rainwater

A frequently used process for hard water is descaling the water using cationic exchangers­­­­­­­­­­­­­­­. With the use of soft rainwater instead of hard drinking water, the purchase of such a system, which costs several thousands of euros is no longer needed­­­­­­­­­­­­­­­­­­­­­­.

For average­ hard water which is softened using such descaling systems, a family additionally requires 25 kg of regeneration salts per year, which can cost approx. € 50.00 ­­­­­­­­­­­­­­­­­­­­­. Of course, with the use of soft rainwater these costs are not incurred­­­­­­­­­­. Also, the wastewater is not loaded with salt­­­­.

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Healthy skin with soft rainwater

The skin is not only the largest organ but also the most versatile human organism­­­­­­­­­­. That means its basic function serves to ensure internal balance. It works as a contact and sensing organ and also as a representation organ­­­­­­­­­­­­­­­­­­­­­­­­.

Soft water above all reduces the danger of irritation for people with sensitive skin­­­­­­­­­­­­.

According to dermatologist Dr. Weyl the skin comes into play here as a sensing organ. The pressure receptors in the lower epidermis react positively to soft water and signal pleasure to the brain­­­­­­­­­­­­­­­­. Hard limescale-containing water together with soap form an insoluble salt that is known as "lime soap" which leaves residues on skin and hair­­­­­­­­­­­­­­­­­­­­. In soft water this unpleasant effect does not occur­­­­­­­­.


In particular, people who suffer from neurodermatitis can have most itching reduced by using soft water­­­­­­­­­­­­­­­­­­­. This applies to all kinds of eczemas­­­­­­­­­. Even with psoriasis and allergic exzema of the scalp, a reduction in the condition can be seen. Soft rainwater not only increases feelings of pleasure and makes the skin more supple but it can also claim medical benefits.­­­­­­­­­­­­­­­­­­­

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Saving laundry detergent

The amount of laundry detergent depends on the water hardness as different tensides, in particular linear alkyl beozole sulphonate (LAS) work depending on hardness­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­. The hardness formers reduce washing power of laundry detergents­­­­­­­­. Corresponding dosing regulations must be indicated on the laundry detergent packaging.­­­­­­­­­­­­­­­­­ Soap foams poorly in hard water because it forms insoluble calcium and magnesium salts.­­­­­­­­­­­­­ For this reason the impact of water hardening is reduced in most laundry detergents by adding phosphates­­­­­­­­­­­­­­.

The need for laundry detergents per family and per year when using rainwater can, in comparison to hard drinking water, be reduced by approx. 2 packages each of 4.3 kg per year.­­­­­­­­­­­­­­­­­­­­ This represents ­a cost savings of € 50.00 / year. This protects the environment and your wallet equally well!­­­­­­

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Soft rainwater protects clothing

As limescale also deposits on clothing, fibres can lose their natural flexibilty and your laundry is then additionally stressed.­­­­­­­­­­­­­­­­­­ Not only do you save laundry detergent but you can also wear your favourite sweater longer.­­­­­­­­­­

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Less shower gel and beautiful hair

Shiny hair during your holiday in Italy, a straw-like feeling after washing it in Munich?­­­­­­­ It’s not your imagination.­­ Our hair not only reacts to shampoo and conditioner, but above all to what comes out of the tap.­­­­­­­­­­­­ Soft rainwater is perfect and even saves shampoo­­­­­­.

If soft rainwater is used instead of hard urban water, hair and skin care products can also be saved.­­­­­­­­­­­­­­­­­­

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No anthropogenic trace elements and drug residues

In Germany each person takes an average of 1-2 medicines per day­­­­­­. Annually ­600 million packages of medicine are prescribed­­­­­­­­­­­. Medicines that we throw away daily largely end up in the toilet­­­­­­­­­­­.

Antibiotics alone remain 70% intact and directly enter the sewage system­­­­­­­­­­­­­­­­­.

Our sewage treatment plants don’t have the option of completely filtering out all of this residual active material­­­­­­­­­­­­­. The hazardous materials can then enter the nearest river or other surfaces where water flows.­­­ ­­­­­­To date, significantly more than 100 medicinal active ingredients have been shown at relevant concentrations in ecological water circulations­­­­­­­­­­­­­­­­­­­­­­­­­­. The natural water circulation flow via rivers, groundwater and drinking water treatment systems have traces of medication with residuals coming out of the tap again.­­­­­­­­­­­­­­­­­­­­­­­­­­­­­

Since properly prepared rainwater is of drinking water quality and additionally does not contain any anthropogenic traces, more and more consumers are deciding to also use rainwater as drinking water.­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­

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Permanent cost-savings for drinking water and wastewater

Water is precious and often plays a role in costs­­­­­. Around the world, prices for water and its disposal are very different­­­­­­­­­­. In Germany, for example on average the costs are already at € 5.00­­­­/ m³. In total, costs for water supply are increasing rapidly: between 2005 and 2013 alone the price per cubic metre as a regional average has increased about eight percent­­­­­­­­­­­­­­­­­­­­.*

Water use in litres / person and day.­­­­ DIN 1989-1, Uni­ver­sity Ol­denburg

a. drinking­; b. cooking­; c. dishwasher­­­; d. washing­; e. brushing teeth; f. bathing - 2 times per week;­­ g. showering­ - 2 times per week­­; h. toilet­­; i. washing­ ma­chi­ne; j. house cleaning­­­; k. car cleaning­­­; l. watering plants­­; m. watering the garden­­­­­

A four person household­­­ with 125.5 l ­consumption per per­son and day comes to 183 m³ per year. This represents­­ € 5.00 costs­ per m³ for an annual­­ water bill ­­­of € 915.00. 

If there is sufficient roof area and rainfall available (for example­­­­­­: a 160 m² roof ­area  in regions with­­ 800 mm of rainfall­­ results in­ 128 m³ of rainwater­­­­­­­ that can be collected over the year), meaning this can be saved by the use of this rainwater alone­­­­­­­­­. If there is insufficient rainwater available ,then AQUALOOP can also recycle grey water­­­­­­­­­­­­.

Whether drinking water and wastewater charges can be saved depends on the municipality (in DE it is mostly only possible to save on drinking water costs.­­­­­­­­­­­­­­­­­­­­).

* Federal Statistics Office­­­­­

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More independence from the drinking water provider

In many countries in the world there are water shortages or power failures resulting in an unstable water supply­­­­­­­­­­­­­­­­. In areas with a good water supply, an independent water supply provides security in emergency situations.­­­­­­­­­­­­­­­­­­



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Higher security thanks to decentralized water supply

With your own water supply, the treatment and the filtration of the water immediately happen on the spot. This can provide an increased security compared to a central water supply because during this long road, dirt can enter the piping system. A further aspect is the theoretical risk of a central contamination or even deposits in the water supply system. With your own water source such a risk is minimized.  

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The Ministry of the Environment recommends rainwater for irrigation of your plants

Soft rainwater is ideally suited for plants in the garden­­­­­­­­. Many plants withstand rainwater better than hard drinking water, for example, rhododendrons or geraniums.­­­­­­­­­­­­­­­­­­­


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Simple retrofitting

To ­date the retrofitting ­­of a rainwater­­­­ system­­ in an existing ­­­building ­­was mostly only thinkable in a complete renovation­­­­­. This was due to the disproportionately ­­­­­­large effort­ required to build­­­­ a separately operating­ water­­­ piping­­ system in the building­­­­­. So­ rainwater­­­ systems­­­­­ are primarily ­­­implemented in new building constructions or for watering gar­de­ns­­­­­. For garden­­ wa­te­r­ing however, hardly any water can be saved, ­in contrast­ to­ using ­rainwater ­­­for flushing toilets­­­ or ­for the shower­­­­­.


The second­­ significant ­­reason was that typical ­­­rainwater ­­­­­­systems only supply water qua­li­ty to the EU basic ­­­wa­ter ­ord­in­ance­­ and so can only be of ­certain­ use­­ in the house, such as for flushing toi­lets­­­­­­­.

With the IN­TE­WA House-RAIN-water ­source­­ both problems can be solved at once­­­­:

  • The requirements­­­­ of the EU regulation for "Wat­er for human­­ consumption­" are fulfilled so that prepared water can be used for body care or for drinking water*
  • The existing piping system of a house can be used. Such a system can thus be retrofitted ideally into many existing homes.

* A test ­­of the drinking­ water­ quality­­ is the sole­­ responsibility­­­ of the user­.

Rainwater treatment system construction


The rainwater is treated in several cleaning stages. Before the water enters the tank, it is pre-cleaned with the PURAIN filter. Coarse debris, such as leaves or small branches, are retained. Particles, heavier than the water, settle on the tank bottom. Lighter substances remain on the surface of the water and are flushed away by the skimmer integrated on the PURAIN filter through the overflow. An integrated backflow preventer stops the ingress of pollution from the overflow.

The 24 V pump installed in the membrane station sucks the water through the hollow membrane fibers into the clear water tank. Bacteria and viruses are reliably filtered without chemical additives, such as harmful chlorine.

The UV system installed in the pressure line combats the potential rein-fection of the standing clear water by disinfecting the water before it is delivered to the consumer via the pump system.

1. PURAIN filter 7. AL clearwater tank
2. PLURAFIT calming inlet 8. AL expansion tank
3. Submersible pump 9. SDS suction hose
4. HORIZON pressure hose 8. RAINMASTER Favorit SC
5. Wall bushing 11. UV-system
6. AQUALOOP Tap comfort 12. Expansion vessel

Simple retrofitting

The existing pipe system of a house can be used. With such a system many existing homes can be retrofi tted.

Your individual system

The modular design of INTEWA technology allows the realization of your own system to suit your structural as well as your personal requirements. If you already have a rainwater tank, this can be used as well.

Questions and answers about your house RAINwater source

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Can I upgrade my existing rainwater harvesting easily?

If you already have a rainwater system, expanding it for the use of rainwater for showering or drinking is also often possible. On the INTEWA WIKI you can first estimate your additional, approximate water requirement. Together with the rainwater collected in your area, you can determine if you have enough rainwater and if your storage capacity is sufficient then.

If not, it should be checked whether you can connect more surfaces.

Alternatively, a greywater recycling is recommended. Reuse the rainwater, with which you took a shower and adjust it to the former existing process water circulation of your rainwater system.

If you have any questions, we're here to help!


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What is the quality of the water from my house RAINwater source?

With the AQUALOOP treatment technique you get, which is normally below the parameters of the local drinking water regulations (except with very high levels of air pollution). In addition, the own water often has other advantages compared with the city water. Here you can find references and test results.

The system operator is responsible for observing and controlling the quality. Make sure that after the initial installation a water analysis is carried out at regular intervals. 

A selection of references


Compliance with and inspection of water quality as well as maintenance of the system is subject to the responsibility of the operator. Cross connections to the public water system are not permitted. The water is only for the operator's personal use and further allowances are subject to local regulations.

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