An infiltration verification an engineer stands behind.

We often handle standard cases within a few working days — counted from the day the site plan and geotechnical report are complete. More complex cases (hybrid systems in poor infiltration conditions, several sub-systems) take correspondingly longer. Turnaround also depends on the flow of information: if, during planning, we need further details to check the feasibility of a solution — additional soil data, say, or a statement from the authority — we ask for them specifically; the time until they arrive extends the delivery time accordingly. The turnaround time is stated bindingly in the proposal — before you commission.

Infiltration verifications (concept) for standard cases from €700 net (from €833 incl. VAT), full planning from €1,500 net (from €1,785 incl. VAT), each at a fixed price. The exact price depends on the property, the type of facility and the available data — you receive a binding fixed-price proposal promptly after the initial consultation — or the specific question about what's still needed for it. No hourly billing, no additional charges for the agreed scope of services.

Because the authority expects not just any calculation, but an auditable, traceable design in accordance with DWA-A 138-1. And because the sizing decides what gets built: type and size of the system follow from the verification — not the other way round. A system assumed by rule of thumb can cost a multiple in construction of what a precisely sized design would have called for. The verification is usually the cheapest part of the project — and the one that determines the size and type of the system.

Yes, that's exactly what the plausibility review is for (€600 net (€714 incl. VAT)): you send us your existing verification, we check it against DWA-A 138-1 and the water authority's review practice and deliver a written review memo. You stay in control — and know where you stand before submission.

Three terms that often get mixed up: the soil (geotechnical) report is produced by a geotechnical engineer — it provides, among other things, the kf value, i.e. how well water infiltrates into your soil. The infiltration verification is the design built on top of it to DWA-A 138-1: which system, what size, with which rainfall data — that is our service. 'Infiltration report' is used colloquially for both; what your authority specifically means is something we clarify in the first consultation. And if a 'soakaway' or 'seepage pit' has been mentioned so far: those are infiltration systems too — which type fits is what the sizing determines.

The water balance to DWA-M 102-4 compares your property's water regime before and after development: how much water evaporates, infiltrates and runs off — and how close the planned condition stays to the natural one. Whether the authority requires it in addition to the infiltration verification depends on the project and the municipality; it is typical for larger projects and in development-plan procedures. We clarify whether your project needs one in the free initial consultation — and if so, we deliver it straight away from the same base data.

Alvaro Burgos Cifuentes, M.Sc., registered member of the Ingenieurkammer-Bau NRW (No. 754661), with professional liability insurance for the planning services. Insurance details: see the About page and legal notice. All calculations and plans are personally reviewed, signed and stamped with the member's stamp of the Ingenieurkammer-Bau NRW.

This happens and is not a warning sign: depending on the location, the water authority may, for example, require an infiltration test (field methods to DWA-A 138-1, Annex A) or laboratory determination to DIN 18130-1, or a supplementary geotechnical report. We tell you already in the initial consultation what is typically to be expected at your location, we formulate the responses to queries and, on request, coordinate the necessary investigations with suitable experts and laboratories — as a separately itemised position, with no hidden costs. That way your procedure keeps moving.

Yes, optionally. The standard service comprises ready-to-submit documents — submission is carried out by the client or the architect. On request we take over the procedure: direct communication with the responsible water authority, follow-up submissions and queries — and where investigations are required, we specify what has to be sampled, where and when, in line with the applicable standard, commission the laboratory or specialist, and check the results before they enter the file. Where we are on site, we accompany the sampling ourselves. For design decisions and plausibility checks we can also take our own indicative field measurements. These are charged as their own item and are not comparable with accredited laboratory analyses: wherever the regulation or the authority requires accredited results, they always come from an approved laboratory. This service is charged separately by effort.