Backflow Protection: Requirements, Installation & Smart Monitoring.

The obligation comes from your municipality's drainage bylaws, and it usually applies to every connected building, not just new ones. The typical wording: the property owner must ensure backflow-free drainage on their own property. Technically, the bylaws refer to DIN EN 12056-4 and DIN 1986-100. In practice:

• Every drain below the backflow level must be protected: floor drain, washing machine, shower and toilet in the basement
• Without backflow protection, you have no right to compensation from the city for backflow damage
• Many insurance companies require functioning backflow protection for claims processing

In short: without backflow protection, you're doubly exposed in the event of damage — no money from the city, possibly no money from insurance.

There are two basic types of backflow protection:

Backflow valve (backflow preventer)

• Passive protection device in the wastewater pipe
• Closes automatically during backflow
• For wastewater without faeces e.g. Type 2; for wastewater containing faeces only Type 3 marked “F” (DIN EN 13564)
• Disadvantage: can be blocked by contamination or calcification

Lifting station

• Active protection — pumps wastewater above the backflow level
• Provides the most secure protection as wastewater cannot flow back
• Disadvantage: requires power, can fail if the pump breaks down

The basic rule under DIN EN 12056-4 and DIN 1986-100: wastewater below the backflow level is discharged via a lifting station. A backflow valve is only enough under certain conditions, for instance if the rooms are of minor use, a toilet above the backflow level is available and you can do without the drains during backflow. Some bylaws are stricter: Dresden only allows Type 3 F valves on foul and combined sewers. What a valve does in detail is covered under backflow valve.

Backflow valves need servicing twice a year, as the German federal flood protection guide (Hochwasserschutzfibel) also states. On top of that, take a look once a month and operate the manual emergency closure. Contamination, limescale, or defective seals can block the flaps. The problem: you only notice the failure during the next backflow event.

Under DIN EN 12056-4, lifting stations are serviced once a year in a single-family house and twice a year in an apartment building: pump, backflow valve, seals, and controls must be checked. During a power outage, the lifting station fails completely — and without monitoring, you won't know.

This is the blind spot: backflow protection isn't "install once and forget". It needs care — and ideally independent monitoring.

Drainbee doesn't replace your backflow protection — it adds an intelligent monitoring layer. The sensor measures the water level in your pump sump or in the collection tank of your lifting station and alerts you to:

• A level above your threshold — for example because the pump doesn't start or can't keep up
• Power outage — without power the lifting station stops
• WLAN loss — so you know when alerts can no longer get through

What Drainbee can't do: check whether a backflow valve in the wastewater pipe closes tightly. The sensor sits in the shaft, not in the pipe. Only regular servicing keeps the valve working.