Small lifting system vs. backflow valve (basement)

Hello,

I want to have a water softening system installed and have now obtained several quotes.

Now I have different statements from the plumber regarding backflow valve and lifting system. Currently, nothing is installed, but there is a small (currently unsecured) drain in the basement for the washing machine, sink, heating, and in the future also for the flushes of the water softening system. This concerns purely wastewater, so no toilet wastewater in the basement.

In particular, a plumber stated that backflow valves are maintenance-intensive (+ not reliable) and that the homeowner’s insurance might not pay if you maintain them yourself, meaning a plumber would always have to come for maintenance.

With the lifting system, a discharge would then be routed to the ceiling of the basement to an already existing (guest WC) drain located at a higher level.

According to the previous owner and own experience, there have been no problems with water in the basement for 3 years, but you never know.

Does it make sense to include the [B]drainage plan here as well? There you can see the heights and the slope to the street sewer.
What is your opinion on this? Advantages/disadvantages

I look forward to your honest opinion; I am a layperson.

In our house, basement floor = rammed concrete a few cm thick, a hole was once made and then a pump sump was concreted. A wastewater pump was put in and then connected via a hose to the wastewater pipe running under the ceiling. This pipe is above the backflow level.

I assume that your basement floor is thicker and maybe even meets different requirements. Therefore, I would consider whether you can close the current drain and then collect all the water you listed in a plastic tank/barrel and then pump it into the sewer with a wastewater pump like I did.

The pump doesn't cost much and is actually low maintenance. And in case of emergency, you can buy it at any hardware store.

The drainage plan should show how the greywater connections in the basement relate to the backflow level in the sewer – in other words, whether anything is necessary at all.

If protection is required and both (RS flap or lifting system) are possible, the lifting system including the loop is certainly the more technically advanced option, but also the more expensive in terms of purchase and installation.
Even if nothing has happened so far, I would act preventively in critical elevation levels with the knowledge of increasing heavy rainfall events.

And regarding maintenance effort: this is at least as great with the lifting system as with the flap. Especially since the installed pump also needs maintenance.