Hello everyone,
We are currently working on building our single-family house. The building application has been submitted, and we promptly received the first letter from the building authority stating:
Rainwater must generally be infiltrated or directed into a nearby open water body, as long as this is possible without excessive effort and damage (§ 48 b Abs. 3 WG-BW).
After a phone consultation with the building authority, we were told that rainwater is not allowed to be discharged into the sewer system due to water protection zone III. The proposed solution (if you can call it that, as they basically said “there’s no way around it”) is a cistern. Permeable paving was also mentioned for the driveway, although we’re not sure what that is for. There is no water body nearby, by the way.
We had actually considered a cistern for watering the garden but excluded it due to the cost. Now we are being forced to install one despite the financial strain, so I have a question for you.
There seem to be countless types of cisterns (according to Google). Can you tell me which type would suit our purpose and where it’s most important not to cut corners?
Kind regards
We are currently working on building our single-family house. The building application has been submitted, and we promptly received the first letter from the building authority stating:
Rainwater must generally be infiltrated or directed into a nearby open water body, as long as this is possible without excessive effort and damage (§ 48 b Abs. 3 WG-BW).
After a phone consultation with the building authority, we were told that rainwater is not allowed to be discharged into the sewer system due to water protection zone III. The proposed solution (if you can call it that, as they basically said “there’s no way around it”) is a cistern. Permeable paving was also mentioned for the driveway, although we’re not sure what that is for. There is no water body nearby, by the way.
We had actually considered a cistern for watering the garden but excluded it due to the cost. Now we are being forced to install one despite the financial strain, so I have a question for you.
There seem to be countless types of cisterns (according to Google). Can you tell me which type would suit our purpose and where it’s most important not to cut corners?
Kind regards
O
Oetzberger17 Mar 2022 17:31I was told it would cost between 2500 and 3000 euros plus the pump... Rip-off companies around here.
Oetzberger schrieb:
I was told something around 2500-3000 euros plus the pump... Rip-off companies around here. I’m not sure where you live, but just in the past few days here in NRW/Lower Rhine, I came across flat-rate offers of around 750 EUR, for example. Flat rate up to 10m (33 feet) depth, with an additional charge of a few euros beyond that.
What’s going on here!? Crazy!
If you have no clue about this kind of stuff, when building a house you usually calculate directly with 5,000€–10,000€ (about 5,500–11,000 US dollars). That’s how it has been with almost everything so far, which is why you get so desensitized and can’t believe otherwise.
That said, as you could read further, a cistern also comes with additional costs that easily add up to a four-digit sum.
It’s an undeveloped lot, so there won’t be anything on that yet. We really hope that a waterproof shell is not necessary; the slope is already going to cause us enough extra expenses.
Because of the slope, we are quite confident that we can manage this soil quite well. On the contrary, we strongly expect to need much more soil.
What does a solution with a cistern and infiltration look like? Two pits next to each other, or can they be cleverly arranged on top of each other?
Unfortunately, we don’t have the space... An infiltration shaft sounds like the soakaway pit mentioned by tomtom79. How exactly does that work?
That’s intense!!! So either it’s a very small house or a very large cistern! I’m guessing the latter…
Yeah, the architect… That’s a topic on its own!! All I can say is “woulda, coulda, shoulda.” It honestly feels like the diploma attached to the building application was bought in Thailand, at least judging by the competence…
We have to submit a “wastewater technical calculation.” I’m very curious how he will handle that…
Uh, so he still wants to save money and is grateful for the tip! I need to understand first what an infiltration trench is and how it differs from infiltration shafts and pits.
Those are also our reasons why at some point we thought it makes sense to install a cistern—for garden irrigation...
What does that mean? A meter for garden water?
What do you mean by that? Why bad enough?
Nemesis schrieb:
What do you always use as a reference? It constantly sounds like a cistern costs 10,000€. What capacity are we even talking about? It’s probably just a three-digit amount, you can’t compare that to a carport or similar... Get a display model from the hardware store (that’s what we did) and you can save a lot.
A simple cistern is not a vital expense.
If you have no clue about this kind of stuff, when building a house you usually calculate directly with 5,000€–10,000€ (about 5,500–11,000 US dollars). That’s how it has been with almost everything so far, which is why you get so desensitized and can’t believe otherwise.
That said, as you could read further, a cistern also comes with additional costs that easily add up to a four-digit sum.
WilderSueden schrieb:
Call your local authority, they should also have a soil report for the site development. That’s usually enough for assessment. If you’re building a basement, I would definitely find out if you need to build with a waterproof shell (also called “white tank” or “watertight shell”) on clayey soil. If yes, then infiltration on the plot is pretty much off the table.
It’s an undeveloped lot, so there won’t be anything on that yet. We really hope that a waterproof shell is not necessary; the slope is already going to cause us enough extra expenses.
Mahri23 schrieb:
The excavation was significant. But fortunately, we could still reuse our soil well on the property.
After all, we still had to fill about 50cm (20 inches).
Because of the slope, we are quite confident that we can manage this soil quite well. On the contrary, we strongly expect to need much more soil.
guckuck2 schrieb:
Just because infiltration is required, a cistern (= retention system) is not mandatory. On the contrary, anyone with a cistern still needs an overflow, either into the sewer or via infiltration (just smaller in size).
What does a solution with a cistern and infiltration look like? Two pits next to each other, or can they be cleverly arranged on top of each other?
guckuck2 schrieb:
The cheapest infiltration method is simply to let the water run into a depression or larger ground area. But for that you need space, which hardly anyone has these days. The second cheapest option is an infiltration shaft. Ask the authorities if that is approved.
Unfortunately, we don’t have the space... An infiltration shaft sounds like the soakaway pit mentioned by tomtom79. How exactly does that work?
WilderSueden schrieb:
Yeah, the pits are huge. Here’s a picture of my pit compared to the foundation slab. The cistern has 8 cubic meters (about 10.5 cubic yards).
That’s intense!!! So either it’s a very small house or a very large cistern! I’m guessing the latter…
netuser schrieb:
The architect should actually take this into account and submit a calculation for the corresponding infiltration trench/infiltration shaft.
At least with us, this had to be reviewed and approved by the local water authority with a fee.
The size ultimately depends on the total amount of sealed surfaces (roof, paving, terrace, etc.) and must be considered accordingly.
Yeah, the architect… That’s a topic on its own!! All I can say is “woulda, coulda, shoulda.” It honestly feels like the diploma attached to the building application was bought in Thailand, at least judging by the competence…
We have to submit a “wastewater technical calculation.” I’m very curious how he will handle that…
TmMike_2 schrieb:
I also meant infiltration trench made from concrete rings for infiltration shafts.
500€ (about 550 US dollars) material cost DIY here. At first, he wanted to save money, hence the suggestion.
Uh, so he still wants to save money and is grateful for the tip! I need to understand first what an infiltration trench is and how it differs from infiltration shafts and pits.
WilderSueden schrieb:
Compared to a well, I don’t know. Compared to tap water, definitely, since you usually have as much fresh water as wastewater and you don’t have to treat water extensively for the garden. And with a cistern, you also save some money on stormwater.
Those are also our reasons why at some point we thought it makes sense to install a cistern—for garden irrigation...
netuser schrieb:
Not necessarily, if you install separate meters for garden water and don’t pay wastewater fees.
What does that mean? A meter for garden water?
WilderSueden schrieb:
Permeable paving is already bad enough, since the subsoil soaks up water two orders of magnitude worse than the paving laid on top of it.
What do you mean by that? Why bad enough?
Oetzberger schrieb:
I was told it would cost between 2,500 and 3,000 euros plus the pump... Rip-off companies around here. They usually charge €70-100 (about $76-$109) per meter of drilling.
For 10-15 meters (about 33-49 feet), they add hefty surcharges for travel with a minimum quantity, site setup, and so on.
But I’m afraid going through a company would have cost me over 2,000 euros as well.
Maybe a regular garden well with a suction hose would be enough for you? That should only cost around 300-400 euros.
However, you need a suitable groundwater level, so ask your neighbors.
Here, in summer when everyone is watering after 4 p.m., the water pressure drops. Then the sprinkler either doesn’t cover everything or wets your building’s facade. That alone was enough reason for me to have my own water supply.
W
WilderSueden17 Mar 2022 17:46nokapito schrieb:
That’s intense!!! So it’s either a very small house or a very large cistern!!! I’m guessing the latter…The house is about 9x10 meters (30x33 feet) without the extension. So not huge, but not very small either. nokapito schrieb:
It’s still an undeveloped plot, so there won’t be any updates yet. We really hope a waterproof concrete shell (white tank) won’t be necessary; the slope is already going to cost us a lot in additional expenses.Make sure to find out for sure. Ask neighbors or get the soil survey done early. If the cistern is on unstable ground, I definitely wouldn’t wait until the end to address the question of a waterproof concrete shell.netuser schrieb:
I’m not sure where you live, but just in the past few days here (NRW/Lower Rhine), I came across flat-rate offers of, for example, 750 EUR. Flat rate up to 10 m (33 feet) depth, with an additional charge of a few euros beyond that.That would be extremely cheap! For a deep well pump? Or just a suction hose?Similar topics