S 1.14 Automatic water drainage

Initiation responsibility: Top Management, Planner

Implementation responsibility: Construction Manager, Building Services Manager

All areas within buildings where water may collect and accumulate or where flowing water or ponding water is not detected or only detected late, and where water may cause damage, should be equipped with an automatic water drainage system and with water detectors. These areas include e.g.:

• basements,
• air-filled rooms below raised floors,
• light wells,
• heating system.

If water drainage is made passively, i.e. by means of floor drain directly into the waste water system of the building, backflow traps will be absolutely necessary. Without such flaps, the water drainage will become an opening for entry of water if the waste water system is above maximum capacity. After extreme rainfall, water enters the basement via this path in the most cases. The backflow flaps must be checked regularly for proper functioning.

If passive water drainage is not possible because the level of the waste water system is too high, pumps that are switched-on automatically by float switches or water sensors can be used. When using this technique, the following should be particularly considered:

• The pump capacity must be sufficiently dimensioned.
• The pressure line of the pump must be equipped with a backflow valve.
• Arrangements must be made so that the pump cannot be blocked by objects floating in the water (suction filter etc.).
• Starting of the pump should be displayed automatically (e.g. to the caretaker or at the Building Services).
• The function of the pump and the switch must be checked regularly.
• The pressure line of the pump must not be connected to a waste water line in its immediate vicinity. In case of a leak in this line, the pump would only pump the water "circularly".

The condition of the property's water discharge must be checked and repaired, if required, to prevent water (e.g. due to heavy rain) from entering the building from outside. If the location or the profile of the property involves special threats to the building due to surface water, the installation of special water protection doors can be considered.

Review questions:

• Are all areas endangered by water equipped with an automatic water discharge?
• Is the functioning of active and passive water discharge systems checked regularly?