ᐅ Backflow Prevention for Gray Water

In our basement, there is only a washing machine, dryer, and a utility sink. The wastewater pipes exit to the outside at about 75 cm (30 inches) height. However, since the basement area with the mentioned wastewater pipe is below street level, a backflow prevention device is necessary. Especially because the building insurance will not cover damages if such a device is missing.

We already discussed this during contract negotiations and wanted to plan for an electric backflow prevention system. Then we were told that this is not required for gray water, only if, for example, a toilet is installed in the basement. We were told that a simple mechanical solution like a ball valve would be sufficient. Now, suddenly, they say we do need an electric system, which leads to additional costs. We had raised this issue beforehand and thought it was settled.

Question: Is a ball valve (I’m not an expert, but it sounds like a purely mechanical solution) sufficient, or is an electric backflow prevention device mandatory? Is it simply installed in the pipework in the basement? What are the costs?

An electric backwater valve costs around 2500€. For greywater, a standard valve is sufficient. Both devices generally need professional maintenance every six months. I am curious how insurance companies handle this in practice.

bluminger schrieb:
For greywater, a standard one is sufficient.

Does a standard one then cost less?
Handling of insurance: I assume in case of damage they will check if one was installed?

Available, sure. But is it maintained as well?

A standard one costs around 700 euros (about 775 USD). Your shell builder will probably get a discount but will likely charge for the installation.

You can upgrade the hatch later, so it’s best to install a conduit or cable now.

What is your opinion on the "ball valve" option as a protective measure? This term has also been mentioned before.