For private clients & building owners · Lower Rhine & NRW
Rainwater, building application, natural pool: what applies to your property?
Whether the authority requires an infiltration verification, whether a cistern pays off, whether your swimming pond needs a permit: we tell you beforehand — and plan review-ready, signed off under professional responsibility, at a fixed price. The authority decides on the permit.
Where do you stand right now?
Four situations that bring private clients to us — and what we do in each case.
It rarely starts with a wish; it usually starts with a question from outside: the building application asks for a verification, a letter from the authority is on the table, the fee notice has gone up — or the last storm showed where the water really goes. In all four cases the first step is the same: we look at your property and your documents and tell you what the authority usually expects, what makes technical sense — and what the planning costs, before you commit.
I am building or converting.
If your project includes an infiltration system, the authority requires a review-ready verification to DWA-A 138-1. We prepare it ready to submit — you attach it to your building application.
Infiltration verificationI have a letter from the authority.
Queries or a request for further rainwater documents? Solvable: we review your documents and state in writing what is missing — an existing verification for €714 incl. VAT.
Plausibility reviewMy stormwater fee has gone up.
The stormwater fee follows your sealed area. Disconnection, infiltration or a green roof can reduce it — on application, under your municipality's by-law. We provide the verification for it.
Guide: reducing the feeHeavy rain left water against the house.
Swales, trenches and retention to the recognised codes of practice — designed so that water is held back where it does no harm. If the water comes from the sewer, see our guide on backflow.
Heavy-rain protectionBeyond obligation: what many people want.
Use rainwater, swim without chlorine, treat wastewater without a sewer — technically proven, but each comes with rules. We tell you which ones beforehand.
Rainwater for garden, toilet and washing machine
A cistern with a cost-effectiveness calculation from your figures — even if the result is "not worth it". Indoors, the rules apply: notification to the health authority (§ 12 TrinkwV) and a separated network (DIN 1989-1); we supply the documents for both.
Rainwater harvestingNatural pool or swimming pond
Clear water through plants and substrate instead of chlorine — if the design is right (FLL guidelines). Swimming pools up to 100 m³ of basin volume usually need no building permit in NRW (§ 62 (1) BauO NRW) — in outlying areas only as an ancillary facility of a building with habitable rooms no more than 50 m away — and permit-free does not mean rule-free.
Natural pools & swimming pondsNo sewer connection: constructed wetland
A planted bed instead of machinery, designed to DWA-A 262. Discharging treated wastewater always requires a permit — the lower water authority decides on the basis of the planning; as a rule, a maintenance contract is prescribed for small wastewater treatment systems.
Constructed wetlandsAI-generated visualisation · illustrative, not a client project
What we tell you beforehand — even when it is inconvenient.
The fee saving is real, but small.
In NRW, stormwater costs a population-weighted average of about €1.13 per m² of sealed area per year (LANUV NRW, wastewater status report 2022; median €0.83/m²). For a detached house that is typically under €200 a year. Whether and how much your municipality credits is set by its by-law — on application.
The verification is not a permit.
We plan review-ready and ready to submit — the competent authority decides on the permit. We tell you beforehand what it usually expects, and we stay reachable for queries.
Not every project pays off.
A cistern does not pay off on every property, a natural pool needs space and care. The cost-effectiveness check (€714 incl. VAT) can end with "no" — and is credited if you then commission the planning.
External services are listed separately.
Geotechnical reports, infiltration tests (field methods to DWA-A 138-1, Annex A, or laboratory determination to DIN 18130-1), water analyses and authority fees are not planning services — they are itemised separately, no hidden items.
Fixed price. One figure before you commission — VAT included.
- Infiltration verification (concept) — review-ready, ready to submit for the standard casefrom €833
- Plausibility review of an existing verification — written review memo€714
- Rainwater cost-effectiveness check — calculation with your figures, clear recommendation€714
- Rainwater harvesting (planning) — sizing, network separation, notification documentsfrom €833
- Swimming pond / natural pool (concept) — feasibility, regeneration zones, permit assessmentfrom €1,428
- Constructed wetland (planning + permit documents) to DWA-A 262from €1,785
Binding fixed-price quote for your property promptly after the initial consultation — or the specific question about what's still needed for it.
Final prices for private clients incl. 19% VAT. Net prices for businesses are listed on the service pages.
What determines the price — process & pricing logicA typical case (illustrative example)
A building owner in the Heinsberg district submits the building application for a detached house; the lower water authority requests an infiltration verification. In the initial consultation we clarify the site plan, the geotechnical report and the connected areas — the fixed price arrives in writing before they commission. If the kf-value is within the infiltration range, a swale is enough; if it is below, we plan a trench or throttled discharge as a variant. The verification goes to the owner ready to submit, who attaches it — the authority reviews and decides.
How it works.
Describe your project
30 minutes by video call, free of charge. Site plan, photo or sketch, geotechnical report if available — if something is missing, we tell you.
Fixed-price quote — in writing
Scope, deliverables, turnaround from complete documents, one figure — or the specific question about what's still needed for it.
Planning & handover
Review-ready documents with a statement of conformity, signed off under professional responsibility. You attach them; the authority decides. We stay reachable for queries.
Frequently asked questions.
Do I even need an infiltration verification for a detached house?
There is no nationwide threshold. In NRW, § 44 LWG NRW applies: stormwater from properties first built on, paved or connected to the public sewer after 1 January 1996 is to be disposed of in accordance with § 55 (2) WHG — infiltrated, allowed to seep away or discharged into a body of water close to where it falls, unless provisions or water-management concerns stand in the way. In practice, water authorities as a rule require the verification as soon as a building project seals new areas. Whether that applies to you is what we tell you in the free initial consultation.
Can I calculate the verification myself?
The authority expects a review-ready design to DWA-A 138-1 with KOSTRA rainfall data and soil parameters. If you already have a verification — self-calculated or from a third party — we review it for €714 incl. VAT with a written review memo, before the authority does.
Does a cistern pay off financially?
That depends on the building — roof area, number of people or consumption profile, and local water and wastewater prices. Blanket savings promises are not serious; that is exactly why the cost-effectiveness analysis with your figures is part of every planning. You see investment, operation and payback before you invest — and if it doesn't add up, we say so.
Does my swimming pond need a permit?
In NRW, swimming pools up to 100 m³ of basin volume usually need no building permit (§ 62 (1) BauO NRW) — in outlying areas only as an ancillary facility of a building with habitable rooms no more than 50 m away. Permit-free does not mean rule-free: development-plan provisions, setback rules and water-law requirements (groundwater proximity, water protection zones, filling and emptying) still apply. From around 100 m³ or in special locations, a permit requirement is to be expected. Whether your project is affected is what we clarify on the basis of your municipality and your property.
Do you also work outside NRW?
Our focus is the Lower Rhine corridor and NRW as a whole — from the office in the Heinsberg district, the Dutch border region is close as well. We also take on projects in the Rhine corridor (Cologne, Düsseldorf, Bonn). Projects across Germany are possible in principle, though with a travel-cost component.
Free initial consultation
One conversation, three answers.
Does your project need a verification? What makes technical sense on your property? And what does the planning cost — as a fixed price, before you commit.
- Free, 30 minutes by video call
- Fixed price before you commission — VAT included
- Signed off under professional responsibility, insured engineering service