We build external sewers, inspection chambers and rainwater drainage in Riga and the Riga region at prices from €25/m.
What an external sewer includes
The external sewer starts where the pipe leaves the house foundations. From there it runs along a trench with an even fall and carries wastewater to the treatment plant or the connection manhole. In a gravity sewer, water flows by gravity alone, so the fall is what matters most: if it is too small, sediment stays in the pipe; if the fall is uneven, spots form where water stands.
- Pipes: PVC or PP external sewer pipes with a stiffness class suited to the soil load; usually 110 mm for the house connection and 160 mm for longer and shared sections.
- Bedding: compacted sand without stones, with a layer of sand above the pipe so that the soil does not crush it.
- Depth: the shallower the pipe, the greater the risk of freezing, so pipes are insulated in shallow spots.
- Inspection chambers at bends, junctions and on long runs, so that the pipes can be inspected and cleaned.
- Ventilation through the house soil stack, so that no vacuum or smell builds up in the system.
Private house sewers: how installation works
- Route We measure the depth of the house outlet and the location of the plant or connection point, and plan a route with as few bends as possible.
- Trench We dig with an excavator, but by hand next to the house and existing utilities. If groundwater flows into the trench, we pump it out.
- Pipes and chambers We lay the pipes on a sand bed, check the fall and install inspection chambers.
- Testing Before backfilling we check the joints and the flow.
- Backfilling We backfill in layers, starting with sand, insulate if needed and restore the surface.
Sewer manholes
A sewer manhole, or inspection chamber, is a point where the pipe can be accessed to check the flow, flush out a blockage or join several lines. At private houses they are placed at bends, where another pipe joins, before the septic tank or connection, and on long straight runs.
| Chamber type | Where it suits | Notes |
|---|---|---|
| Plastic inspection chamber (corrugated pipe with a base) | Yard, lawn | Light, watertight, quick to install; the lid must match the load |
| Concrete-ring manhole | Driveways, great depths | Durable but heavy; the joints must be sealed |
| Cleanout pipe (no chamber) | Short runs | Lets you flush the pipe but not look into it |
Many older houses have concrete-ring sewers with concrete manholes. If the rings have crumbled or shifted, the manhole lets in groundwater and sand, and the pipes clog more often. The manhole lid must match what will drive over it: a light one is fine in a lawn, but a driveway needs one designed for vehicle loads. More: installing inspection chambers.
Rainwater drainage
A rainwater drain is a separate system that collects water from the roof downpipes, terraces and driveways. It is not connected to a septic tank or BIO plant: in a downpour the tank overfills, septic tank sediment is washed out into the drain field, and a BIO plant has its activated sludge flushed out.
Rainwater is discharged into a ditch, infiltration crates or soakaways on your own plot, or into the city storm sewer if there is one and the connection has been approved. Sand traps are needed at the downpipes, because without them sand and leaves gradually fill up the pipes. More: rainwater drainage installation.
Connection to the mains sewer
If there is a mains sewer network in the street, a connection is usually simpler than a septic tank in the long run, because there is nothing to pump out or maintain. The connection procedure is set by the municipality's binding regulations, and the work requires technical conditions from the water utility; in Riga this is Rīgas ūdens (Riga's water utility).
After connection, the old septic tank is pumped out, disconnected and filled in or removed, so that the empty tank does not collapse. On documents and municipal co-financing: connecting to the mains sewer.
Law on Water Management Services, Section 6, Paragraph Four, Clause 1 (the municipality's binding regulations set the procedure for connecting to the centralised sewerage system), likumi.lv/ta/id/275062, version of 01.07.2025. Checked on 30 October 2026.
How much sewer installation costs
External sewer installation costs from €25/m. The price per metre depends on:
- the digging depth and the soil (clay, stones, groundwater);
- whether an excavator can be used or the digging has to be done by hand;
- the number of manholes and the insulation;
- restoring paving, asphalt or lawn;
- whether a sewage pump station is needed if a gravity fall cannot be achieved.
All prices: prices.
Common mistakes we have to fix
- A pipe with no fall or with a sag: water stands in it and sediment builds up.
- Sharp bends without an inspection chamber: blockages form there and cannot be flushed out.
- Rainwater connected to the septic tank.
- A shallow pipe without insulation freezes in winter.
- Pipes laid on stones or construction rubble: over time the joints come apart.
- Indoor sewer pipes used outside: they are not designed for soil loads.