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Replacing an old sewage holding tank or cesspit: where should you start?

Many Estonian properties still rely on an old pit or tank of concrete, brick or steel — often called a lampkast — or on a holding tank that has worn out. Replacing old holding tank structures is more than a digging job. The new sealed sewage holding tank (reoveemahuti; in legal texts reovee kogumismahuti; UK readers may know it as a cesspool or cesspit) needs its own paperwork, and the old one must be emptied, decommissioned and reported. Start by establishing what is in the ground, whether public sewerage is coming and what your municipality’s rules say.

Why old concrete, brick and steel tanks fail

A holding tank treats nothing and has no outlet: it stores wastewater until a tanker pumps it out (purgimine). The Water Act (Veeseadus) § 124 therefore requires holding tanks to be leak-tight (lekkekindel). Old structures often are not:

  • Material. The Ministry of the Environment’s 2015 guide for rural wastewater systems says tanks are now usually fibreglass (GRP) or polyethylene; metal and reinforced concrete are not recommended, because their long-term watertightness generally cannot be assured.
  • Construction and age. Guidance for municipal inspectors, published on the Ministry of Climate’s (Kliimaministeerium) website, says brick tanks and tanks with cracked walls are mostly not leak-tight, and cites studies in which nearly half of on-site wastewater systems were not leak-tight. Its typical defects include unanchored tanks shifted or broken by high groundwater, structures deformed by soil pressure, and worn-out systems.
  • Hidden outlets. The same guidance has inspectors check an emptied tank for a proper bottom and walls, and for outlet openings, which may mean wastewater goes untreated into the environment. A pit with an outlet is not a holding tank at all.

Municipal rules can demand action: Saaremaa’s require a worn-out system, or one that endangers soil or groundwater, to be rebuilt (§ 7(8)). Warning signs are covered in Is your sewage holding tank leaking?

Before you dig: four things to settle

  1. What is in the ground. A holding tank has an inlet and no outlet; a septic tank (septik) drains to an infiltration field. Ask the municipality (kohalik omavalitsus) whether the old structure is recorded in the Building Register (ehitisregister) — an old one may not be. If it is not, ask whether its removal still needs a demolition notice.
  2. Whether public sewerage is coming. Once your plot’s connection point is built, you must connect by the deadline in the municipality’s development plan, or within four years of the connection point’s completion if it sets none — unless wastewater collection and treatment are ensured in another way that meets Water Act requirements (Public Water Supply and Sewerage Act, ÜVVKS, § 17(3)–(4)). Kohila, for example, lets a tank installed before the sewer was built stay in use for only four years after the sewer’s use permit (§ 3(4)). Ask before you invest.
  3. Where the new tank goes. The old spot is not automatically right. The national setback (kuja) regulation does not cover holding tanks, but municipal rules may; the tanker needs access in every season; and the 2015 guide notes that a system on someone else’s land can be rebuilt there only with the landowner’s consent.
  4. What size you need now. A pit dug for weekend use may be too small for a family living there all year. Size the new tank from your own water-meter data, using the method in What size sewage holding tank do you need?

Paperwork: notices for the new tank and the old one

Under the Building Code (Ehitusseadustik), a replacement involves up to three notices to the municipality:

Notice Covers When
Building notice (ehitusteatis) Installing the new tank and demolishing the old one; Annex 1 lists no building permit or design documentation for a holding tank Through the Building Register, at least 10 days before work starts (§ 36)
Use notice (kasutusteatis) The new tank (Annex 2) Through the Building Register, at least 10 days before use; if the municipality announces no further checks within 10 days, you may start using it (§ 48)
Notice of complete demolition The old structure, if it required a permit or notice; gives cadastral code, address and Building Register code At least three days after demolition (§ 43(3)–(4))

Under § 4(4), demolishing a structure and building an essentially similar one in the same place — among other things, of unchanged volume and purpose — may be treated as rebuilding; if the new structure is essentially new, it counts as one demolition plus one new construction. Whether one building notice may cover both jobs is for your municipality to say, so ask before you file.

For the notice’s description of the tank, have its model and dimensions ready; per-model drawings in PDF and DWG are in the model table. What municipalities ask for when the new tank is taken into use is explained in Sewage holding tank rules in Estonia.

Order of work. The new tank may be used only after its use-notice period, so the old one normally stays in service until then; the example rules below allow for that. The usual sequence:

  1. Check the site and your municipality’s rules.
  2. File the building notice.
  3. Install the new tank.
  4. File the use notice at least 10 days before use.
  5. Empty and decommission the old tank.
  6. Report the demolition.

Decommissioning the old tank: what municipal rules require

The detailed steps are in each municipality’s rules for on-site wastewater (reovee kohtkäitluse ja äraveo eeskiri, Water Act § 104(7)). Three examples, not national rules:

Saaremaa (2019 rules) Jõelähtme (wording from 15.11.2025) Kohila (2021 rules)
Before work Building notice for demolition (§ 8(2)) Same requirements as for building (§ 7(1)) Building notice 10 calendar days ahead (§ 8(2))
Emptying Emptied, then washed clean by the emptying company; contents and washing water go to it (§ 8(1), (3)) By an emptying company (§ 7(2)) By an emptying company (§ 8(3))
The structure As a rule demolished and, where required, removed; pit filled with sand, gravel or clean soil (§ 8(1)) Pit or emptied tank filled with soil; a cleaned tank may collect rainwater (§ 7(2)) Pit filled with soil or emptied tank with sand; reuse, e.g. for rainwater, if harmless and lawful (§ 8(3))
Demolition waste Under the municipal waste rules (§ 8(3)) To a licensed company; not to be buried or used to fill the pit (§ 7(2)) To a licensed company; not to be buried or used to fill the pit (§ 8(3))
Afterwards Demolition notice with a work description and construction-waste statement (§ 8(2)) Work description and waste documents (§ 7(3)) Within 5 working days: work description, proof of disposal of demolition waste and sludge (§ 8(4))
Deadline Within 3 months after the new tank is taken into use; within 1 year of connecting to public sewerage (§ 8(4)) Within 3 months after the new system is built; within 1 year of connecting (§ 7(4)) Within 3 months after the new system is built; within 1 year of connecting (§ 8(5))

Municipal rules differ and are amended from time to time, so check the current wording of your own municipality’s rules before you start.

In practice:

  • Keep the final emptying receipt and the waste documents — the proof these rules ask for — and have your installer price demolition, backfill and waste disposal as separate lines.
  • Stay out of the pit. The 2015 guide, describing a trial pit, warns that nobody should climb into an excavation because its walls can collapse — the same caution applies here.
  • Keeping the old tank for rainwater? Keep it separate from the new holding tank — Kohila’s rules, for example, require rainwater to be kept out of on-site systems (§ 4(4)).

Buying a used tank instead of a new one: the risks

A second-hand tank can look like a cheap replacement, but much of what matters cannot be seen:

  • Unknown history. It has been installed, dug out and moved, and the defects listed above can happen underground. Ask to see it emptied and cleaned, inside and out, and ask how it was anchored and why it came out.
  • Material limits. These are product-specific: Vesmaco’s order drawing, for example, gives pH 3–10 and a temperature tolerance of 60 °C for its GRP. Without the maker’s data for a used tank, you cannot tell whether what it has held stayed within its limits.
  • Documents. Saaremaa wants the manufacturer’s certificate and/or CE marking with a declaration of performance with the use notice and, in justified cases, a leak-tightness assessment by a qualified person (§ 5(4)). Kohila accepts only tanks certified to European standards and installed according to the product’s instructions (§ 4(2)–(3)).
  • Warranty. Do not assume a manufacturer’s warranty passes to a second buyer; ask the manufacturer — see holding tank certificates and warranties.

Before paying, ask your municipality whether it would accept the tank with the papers that exist.

Frequently asked questions

Can I leave the old tank in the ground? That depends on your municipality. In the examples above it is always emptied first; Saaremaa expects demolition as a rule, while Jõelähtme and Kohila also allow an emptied tank to be filled with soil or sand, or cleaned and reused for rainwater — never filled with demolition waste.

Can the new tank go into the old pit? Only if the spot still meets your municipality’s setback rules and the tanker can reach it. The pit must also be prepared as the manufacturer requires — Vesmaco’s installation guide calls for a compacted bed of at least 20 cm of stone-free sand and compacted backfill in 30 cm layers, which old fill and rubble do not provide. Your designer or installer decides.

Do I need a building permit to replace a lampkast? Not for the holding tank: the Building Code lists building notices for installing the new tank and demolishing the old one, and a use notice for the new tank. A tank within a house’s building-permit project is covered by that permit application (§ 35(5)). Your municipality may add requirements.

Planning a replacement? Ask for a quote. Tell us how many people use the property and for how much of the year, your water-meter readings, the depth of the sewer pipe at the house and how a delivery vehicle and tanker reach the spot — and ask for a model suggestion with its drawing for your building notice. Use the quote form or call +372 641 8550. Vesmaco manufactures the tanks and provides consultation, design and delivery in Estonia; emptying and removing the old tank and installing the new one are arranged with the emptying company and your installer.

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