How Bilby works
Private wastewater system costs
Installation plus any configured application fee
For a plot outside municipal wastewater service, Bilby can combine a regional system range with a municipality-specific application fee. The fee is included only when municipality and estimate year match. If project-specific amounts are absent, the budget reference is 100,000/160,000/280,000 SEK for ordinary one-household private wastewater scope.
A solution must still be selected and accepted
The reference covers normal installation and groundworks plus a modest permitting allowance. It does not select a treatment technology or establish approval. Annual service, the well, municipal sewer fees and exceptional rockwork are excluded. A regional result with an explicit application fee must not receive that fee again; the national reference already has a small permitting allowance. The private package owns well and wastewater details. A mixed service arrangement should contain only the missing private service.
Cost inputs and review evidence
Risk evidence informs the need for review without changing the configured installation range automatically.
| Input | Unit | Origin/use |
|---|---|---|
| Wastewater service-area status | status | Analysis determines likely private need |
| Regional installation low/high | SEK | Configured allowance |
| Municipality fee and tariff year | SEK / year | Matching local configuration |
| Soil, depth, groundwater, slope, water proximity | evidence | Warnings, not price multipliers |
| Selected approved system price | SEK | User/contractor replacement |
How the amounts are combined
When private wastewater is likely, the regional function takes low/high installation amounts and adds the same applicable fee to each. If the fee is missing or from a different year, it adds no fee and discloses that omission. If both private services are needed it adds the well range once. Clay or low permeability, shallow bedrock, high groundwater and other constraints add warnings. They do not automatically move the range upward or choose an engineered treatment system. A stored project result takes precedence over the fallback; a stored combined utilities amount can retain ownership until it is reconciled.
Illustrative regional installation
With fictional regional system costs of 110,000–230,000 SEK and a matching configured 10,960 SEK fee, wastewater totals 120,960–240,960. If a 90,000–150,000 well is also required, private VA totals 210,960–390,960, with midpoint 300,960 if shown in the budget. A clay warning leaves these amounts unchanged. National fallback for both services is a different 180,000/290,000/530,000 SEK package.
Approval and ground conditions remain open
A low/high range is a planning allowance, not approval likelihood or a statistical confidence interval. Unknown service-area evidence must not be read as a confirmed private requirement. The municipality and installer need to assess location, discharge requirements, groundwater and the chosen system. Confirm whether the quotation includes application, excavation, pipes and reinstatement; subtract overlapping package scope.
Scope and dates
Code reviewed 18 October 2026; national reference research 16 September 2026. Havs- och vattenmyndigheten’s guidance on small wastewater systems informs regulatory scope, not Bilby’s installation coefficients. The current municipality application tariff is the fee source; the example fee is a fictional configuration input, not a freshly verified local tariff.
The review date covers this explanation and its implemented method. Price and data dates are stated separately in the article.