ᐅ Wastewater from the downpipe to the house connection: reliably leak-proof?

Hi,
we have replaced our wastewater pipes both inside and outside the building. Now we have a downpipe leading into the basement and an external wastewater connection that also enters the basement. These two need to be connected. Basically simple—PVC pipe puzzle and hose clamps *done*.

That’s what I thought, too. Our neighbor’s basement flooded during the recent heavy rain because his PVC pipes were apparently not installed securely. The pressure on the first 90-degree elbow was so high that the clamp just above it pulled apart. Result: basement full of water...

If I’m doing it now anyway, I want to do it properly. But how? Which clamps are the right ones here? The materials at the hardware store don’t seem like the best choice, and the local specialist dealer seems to have forgotten how to give proper advice ([...]We only have the same ones as at the hardware store, nothing else available[...]).

Am I being too critical? How have you solved this problem?

Thanks,
your Parcels

1) The clamps are not meant to hold the pipes together – so how could they pull them apart? I think your neighbor doesn’t really know what happened there.

2) 90-degree angles have no place in wastewater pipes.

3) The pipes must be fully inserted into each other; the clamps are used to adjust them on the wall or ceiling. There is nothing better or worse than what you can find at a hardware store.

4) If you have to puzzle the system together, something has already gone wrong. Downpipe, two 45° elbows, a short straight section, inspection chamber – done.

The internal pressure in the wastewater pipes also acts along the pipe length and can pull pipes out of their seals. The system is designed for gravity-flow, non-pressurized wastewater.

During flooding or blockages, water can back up and may pull pipes out of their seals.

Wall-mounted clamps installed before and after bends secure the pipes within the seals even under slight pressure.

In the event of flooding, water will be pushed up from the lowest point, such as toilet, shower drain, or sink drain.

For this purpose, shut-off valves are installed, which can or must be closed during flooding.

Lumpi_LE schrieb:

1) The clamps are not meant to hold the pipes together – how should they pull something apart?
I think your neighbor doesn’t really know what happened there.

I thought so too. I checked it myself in the basement; there is a KG2000 pipe "Green" with double seal entering the house. The elbow is simply pushed backward, and the clamp just above it is completely deformed.

Lumpi_LE schrieb:

2) 90-degree elbows have no place in wastewater pipes.

Correct, two 45-degree elbows make 90 degrees for me. However, I didn’t write it exactly like that here, sorry for that.

Lumpi_LE schrieb:

3) Pipes must be fully inserted into each other; the clamps are used for alignment on the wall or ceiling. There is nothing better or worse than this, even in hardware stores.
4) If you have to puzzle the system together, something already went wrong. Downpipe, two 45° elbows, short straight piece, inspection chamber – done.

See points 1 and 2.

If it gets as severe as it has for many people in recent days, I can well imagine that the pipes could be pulled apart by the water pressure. Off the top of my head, I would have installed more clamps before and after the connections so that the pressure is better distributed across the clamps.