Mechanical backflow prevention for fecal matter

Hello everyone,

this is my first post here.

First: Yes, I know that according to DIN a mechanical backflow preventer for wastewater containing feces is not allowed.

However, I want to know why. I have done some research and interestingly it seems to be completely common and accepted (legally and by insurance companies) in the USA, Canada, and also Switzerland to use a mechanical backflow preventer even for wastewater containing feces. Either as a simple or double flap, also with additional manual operation.

In our new build without a basement, on a slight slope, the prefab house manufacturer considers the next higher manhole cover as the backflow level. Normally, wastewater does not flow uphill, of course.

Rainwater is directed into a separate channel. So it is "only" about wastewater, and here only from the ground floor.

I have the option to have the prefab house manufacturer prepare the installation of a backflow preventer for the ground floor of the single-family house (there is also a toilet on the upper/floor/attic) only and to have the installation of the backflow preventer done on site or arranged to be done.

I am not only deterred by the high costs of a possibly unnecessary electrically operated and electronically controlled backflow flap but also by the required maintenance twice a year by a specialist company. This will cost a multiple of the actual flap including installation, etc., over the financing period of the house.

Therefore my question: If a mechanical flap is sufficient in other first-world countries, why should it not work here as well? I would be readily willing not to comply with DIN if the associated risk in practice is negligible.

I look forward to your qualified opinions.

Regards

Stefan

A purely mechanical flap, which is normally open, and therefore supposed to be suitable for fecal matter. (even if it is not allowed in Germany according to DIN....)

Nice patent, but it doesn't help. In case of damage, the insurance does not pay because it is not DIN-compliant. We also tried to buy a mechanical flap, but it was not available on the market. Here in Germany, only electronically controlled flaps are distributed. In addition, at least in our area, during heavy rain etc., the municipal utilities distribute the water masses throughout the entire sewer system. This can lead to full sewers even in residential areas without flooding risk. Considering the weather extremes of recent years, I find having a certain safety buffer quite sensible. We installed it voluntarily; according to the expert, it was not absolutely necessary. But of course, you can do it like the railway: Quote from WDR today: "When purchasing ICE air conditioning systems, the railway made mistakes in the past. "The then railway boss Mehdorn was of the opinion that in Germany it would not get colder than minus seven and not warmer than 26 degrees - at most 30 degrees in peak." The railway has recognized the problem and is in the process of retrofitting - but the conversion simply takes time." I imagine that retrofitting an electronic backflow valve with maintenance shaft and piping, etc., is much more difficult than installing it right away during new construction.

Hello dream catcher,

thank you for your contribution.

I am explicitly not concerned about the insurance. If the backwater valve does what it is supposed to do, I will not have an insurance claim. I am willing to live with the minimal residual risk. I don’t really have the full coverage mentality.

By the way: I just discovered that even the company Kessel in their English brochure (of course not in the German one...) says that the mechanical valve Staufix SWA is also suitable for sewage (with the note to check the regulations in the respective country).

I have the impression that something unnecessarily complicated and expensive is being imposed on us in D and the EU. And with the fear of sewage in the house, of course, you can make good money. The manufacturers must have done good hobby work when creating the applicable DIN....

Regarding the weather: Rainwater is completely separately routed here, and there is no risk of backflow into the house here either. This is only about wastewater from the ground floor.

Regards

Stefan

You can question that throughout the entire house construction. Even the [Energieeinsparverordnung] prescribes many things to you, etc. Pressure guards for ovens that don't bring anything, etc.

Either you comply with the regulations or you don't.

You can get a mechanical backwater flap at any hardware store or from any building materials dealer! You have to weigh the risk for yourself.

You can question that throughout the entire house construction. The Energy Saving Ordinance also prescribes many things, etc. Pressure switches for stoves that do nothing, etc. Either you follow the regulations or you don't.

That is probably true. At least I agree with your first paragraph. However, when it comes to backflow prevention, I really find it hard to just accept the expensive solution simply because the DIN standard demands it, especially when boilers in other markets indicate otherwise.... Stefan