Problem with inlet and outlet height for 4Rain flat tank 5000 liters

Hello MKoni

I did it this way after consulting with the relevant department and to save the corresponding fee (several hundred euros per year).

In the tank there is a simple wastewater pump from the hardware store for about 40 €. This was installed quite high up to prevent the water level from getting too high. I quickly took some pictures.

Picture 1 shows the pump and the connection that ensures the water level does not get too high. In the foreground, you can still see a pipe that leads to the pump standing on the tank floor (same pump as above) with which you can water the garden, but as a precaution, not with a sprinkler because I am afraid the nozzles will clog since I have not installed a filter anywhere.
At other times, this second pump also serves to remove water from the tank if the inflow is higher than what the first pump can handle or if pump 1 has a defect. Then, however, it empties almost everything (controlled by a float switch).

Picture 2.
Here you can see the hoses going into the 75 mm wastewater pipe I laid.
This pipe lies above ground in the garden. I cut it on one side with a circular saw (Picture 3). The individual 2m pieces were then connected without the sealing gaskets so that the individual pieces can be easily twisted, which allows you to adjust how much water should flow out and where. Since this pipe is located in an area where wild garlic grows, you cannot or hardly see this pipe at the moment, as you can see in Pictures 3 and 4. This means you can hide these pipes through clever planting.

As for gluing the dome, I would not do it because you cannot be sure it will be watertight. In the event of a dome replacement, you would also have difficulty removing it again. So I would not do it. You could try silicone once, but I doubt it will help.

Question: Is the dome really just placed on top? I ask because our dome was screwed onto the tank and there was also a corresponding gasket.

Since water does not like to flow uphill, it will not work to connect the overflow to the higher-lying sewer. Water will only flow into the sewer if the water level in the tank is as high as the sewer connection and thus above the tank/dome connection point.
If there is a leak at the tank/dome connection, you could have problems.
As already said, either lower the sewer connection overall or use a pump. I can't think of anything else right now.

And one more note. I once read that in winter, with flat tanks, you should try to keep as little water as possible in the tank to prevent ice formation and possible damage to the tank. As I said, I read this somewhere; whether it is true or not, I cannot say.

So, I just want to say thanks for your EFFORT!!!

I want / will use the tank so that I can irrigate the entire property and thus also use the sprinklers (recessed in the lawn) as well as various connection sockets for a hose connection. I ran the system this way at our first home for over 5 years and it worked wonderfully. I specifically bought a powerful submersible pump that can operate up to 5 sprinklers simultaneously over a distance of 20m. There is also an inlet from the household water to short-circuit the system when there is no water in the tank.

So I am still pondering because I want to avoid an additional pump.

The tank has the option to create a hole on the side for connecting another tank. If I install the supply line here, I would be outside the DOMS and would have an inlet at the same height in the tank!?! Then I would need to clarify how to accommodate the filter because the basket is not feasible; here I could use one that works with 0 slope.

How about operating the pump using a water differential switch. Then one pump would be sufficient. It would look a bit strange if the sprinkler suddenly starts operating when it rains. But that would probably also be an option. Such a device costs about €46 depending on the dealer. I would like to send you the exact designation by email but at the moment I can’t find a way to do that here.

That is a good idea also for my drainage shaft if not everything seeps away.

I think you mean something like H-Tronic level controller filling, emptying 10 m 1114455.

However, yesterday I looked at the main body again. The connection for the overflow is on one side of the tank, and on the opposite side there is the same flat spot for a hole. I could easily set this 5-8cm lower than the connection on the other side, the respective seals are available individually. This would create a slope, everything would be inside the tank without involving the DOM, I would just have to get the appropriate filter because it would not go through the filter basket.

Yes, exactly something like that. I use the 3000 Plus just in case.

Regarding the filter, I can’t say anything because it was deliberately omitted here. Maybe you can bury a small barrel in front of the tank or build a shaft where the inlet and filter are installed, and then it goes further to the tank, so you can use the inlet connection on the tank. Of course, you could also set the tank deeper. You can’t see it in my picture, but I also had to set the tank deeper because of the height of the supply line, and then there were two options: either to buy a rather expensive manhole extension or to build a shaft. The decision was to build the shaft.
Did you have a tank at your first home, too? I ask because I’m not so sure whether your information refers to the tank or the irrigation.

Maybe you could also post a few pictures with markings where you plan the connections. It might be somewhat easier for me to make suggestions or to imagine exactly what you’re planning.