After settling, the wastewater runs by gravitation to a pump well with a small electrical pump, since gravitation will not spread the wastewater effectively in the basin and the willow growth will not be optimal. A pump for a normal household will consume around 30 kWh a year.
The willow trees are planted on either side of the water spreading system. The types of willow trees have been selected specifically for this purpose and a combination of different varieties is used to have the system perform optimally. The willow trees must be planted in early spring. In this way, the willow trees will grow up and empty the soil during spring summer and autumn, so that there will be sufficient room in the soil for wastewater and rain falling directly in the facility during the winter.
Nutrients from waste water are effectively up-taken in the willow stems and foliage and approx. 10-20 tonnes of dry matter per hectare are produced. The facilities will not affect the environment around it because it is completely closed by means of a non-permeable membrane made of polyethylene. On both sides this membrane is protected against damages from stones in the soil. This means that willow wastewater cleaning facilities can be used, also where wells are placed near the facilities without spoiling water quality from bacterial infections. It is important that households using willow wastewater cleaning facilities use soap, detergents, personal hygiene products, cleansing agents and so on that are naturally digestible. (All other types of facilities for wastewater should have the same attention on this issue). In that way substances will never be accumulated in the soil and the soil can be used as arable land after using the facility even after hundreds of years. Xenobiotic substances will in a willow facility be given a lot of time to be digested and area with the right moisty condition for bacteria will go up and down the soil many times during a year depending om rainwater amounts falling in the facility. This will create moving zones with excellent conditions for bacteria to degrade xenobiotic substances as hormones etc. Also, the big size of willow facilities will mean a small load per area unit and this means that a willow facility will be even more stable than other types of facilities for treatment of wastewater.
The zero-discharge willow purification systems have been used for treating industrial waste water with good results. In industrial applications, the quality of waste water can be very different depending on the source and so the willow purification facility must be designed considering the specific quality of the waste water.