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Sewage holding tanks for year-round homes: planning your system

A sewage holding tank for a house you live in all year is a different proposition from one at a summer cottage: a family fills it every week or two, in every season, and every litre has to be driven away. A holding tank (Estonian reoveemahuti; in legal texts reovee kogumismahuti; a cesspool or cesspit to UK readers) only stores wastewater until a tanker pumps it out (purgimine) — no treatment, no outlet. It suits a permanent home if you plan it as a routine: the right volume, a level alarm, an emptying arrangement and careful water use. This article covers all four, and when the law leaves no other option.

What the official benchmark means week by week

Estonia’s official guide to on-site wastewater systems (Ministry of the Environment, 2015 — dated, but still on the ministry’s website) uses a planning figure of 100–150 L of wastewater per resident per day. For a four-person family living permanently it gives an optimal tank size of at least 5 m³, emptied once a week.

The arithmetic, with every assumption visible:

days between emptyings = usable volume (L) ÷ (persons × litres per person per day) emptyings per year = 365 × occupancy share ÷ days

Four people produce 400–600 L a day. Taking usable volume as nominal volume for simplicity (in practice the alarm level leaves a reserve, see below), 5 m³ lasts 5,000 ÷ 600 to 5,000 ÷ 400 = 8–12.5 days; the tanker must be ordered before the tank is full, hence “weekly”. Over a year (occupancy share 1) that is 146–219 m³ driven away in 29–44 visits. Your own water-meter data beats the planning range: monthly m³ × 1,000 ÷ days = litres per day.

That is the drawback, stated plainly: nothing is treated on site, so emptying is the running cost, and in a permanent home it never pauses. The routine that keeps it manageable: when the alarm sounds, order the tanker; keep the access route clear; file every emptying receipt; read the water meter once a month.

Pick the tanker rhythm first, then the volume

A bigger tank does not remove a litre less per year; it spreads the same volume over fewer visits. So choose a tanker rhythm you can live with, then read off the volume. Same assumptions as above; cells show days between emptyings · visits per year.

Household 5 m³ 8 m³ 10 m³ Driven away per year
2 people 17–25 days · 15–22 27–40 days · 9–14 33–50 days · 7–11 73–110 m³
4 people 8–12.5 days · 29–44 13–20 days · 18–27 17–25 days · 15–22 146–219 m³
6 people 5.5–8 days · 44–66 9–13 days · 27–41 11–17 days · 22–33 219–329 m³

Tanker capacity caps the choice: the guide says small tankers (paakauto) hold 4–5 m³ and the largest about 10 m³, and a tank bigger than the largest local tanker cannot be emptied in one visit — ask local operators what they use today. In one situation the law also sets a minimum volume (see the emptying section).

Then round up: Vesmaco lists every volume from 5 to 10 m³ in two diameters (larger diameter: shorter tank, deeper excavation), plus 12 and 15 m³ — see the model table. The full sizing method is in What size sewage holding tank do you need?

These figures assume somebody is home every day. For part-year use see holding tanks for summer houses; if you take paying guests, size for the peak — see holiday rentals and campsites.

A permanent home also runs through the winter: the ministry guide advises insulating with moisture-resistant, load-bearing polystyrene board where the cover over the pipe or tank is less than about 1.3 m. If your tank, riser or inlet pipe will lie that shallow, ask the supplier and your designer or installer how to insulate them on your site.

A level alarm set to your tanker’s notice time

The ministry guide calls a level sensor advisable; at intervals of one to three weeks it is what makes emptying a routine.

Vesmaco’s order drawing lists an overfill alarm as an option; the site carries sheets for two wireless alarms, the Smartel Tank-Check RF-431 and the Vesmaco Cesspool Alarm. Compare the datasheets or ask the supplier which one comes with your tank. Per the RF-431 sheet, an indoor receiver gives a red light and buzzer 2 minutes after liquid reaches the sensor in the tank, and a separate “no connection” alarm after about 30 minutes without radio updates — which also catches a flat transmitter battery.

The setting that matters is the alarm height, fixed by the sensor cable length: leave room above the sensor for notice days × daily wastewater. If your emptying company needs three days’ notice (an assumption — ask them), four people need 1,200–1,800 L — roughly a quarter to a third of a 5 m³ tank, so the alarm sounds after about 5–9.5 days; in a 10 m³ tank, after about 14–22 days. That is why 5 m³ is a minimum for four, not a comfortable size. The volume usable up to the alarm is somewhat below the nominal volume, so check the drawing and the alarm height for your model.

Without an alarm, the guide’s method is a dipstick: order the tanker when the level passes about half the diameter. Either way, the tank must never overflow. More in Sewage holding tank level alarms.

Arrange the emptying service before the first flush

Who organises emptying depends on the address.

In a sewage collection area (reoveekogumisala) of 2000 population equivalents or more where public sewerage has not been built, the Public Water Supply and Sewerage Act (ÜVVKS) § 47 obliges the water company to organise the emptying service (purgimisteenus) at your request. Your tank must be leak-tight, accessible to the emptying vehicle and able to hold at least two weeks’ wastewater — on planning figures 5.6–8.4 m³ for four people. The service is yours twice per calendar month at the same per-m³ charge as for customers connected to public sewerage in the area, plus any monthly subscription fee (§ 48(2)–(3)). Ask the water company how it assesses the two-week volume and how any additional visits are handled.

In other cases you normally choose an emptying company yourself; Water Act § 124(2) makes the producer of wastewater responsible for arranging transport to the reception point (purgimissõlm) named in the municipality’s public water supply and sewerage development plan. Check your municipality’s rules for any local arrangements.

Settle before you move in:

  • the load the tanker takes in one visit;
  • whether the charge is per visit or per m³;
  • the days’ notice needed, summer and winter;
  • how close the vehicle must get and the hose length;
  • a receipt every time — municipalities may ask for proof of emptying (Saaremaa vald, for example, requires one for each visit).

Budget with your own local price: annual cost = emptyings per year × local price per visit, or m³ per year × price per m³.

The ministry guide calls for tanker access in every season and says the truck must not drive over the tank — in winter, keep the route and the cover clear of snow.

Use less water: the main lever on running costs

Almost everything that passes your water meter ends up in the tank. On the planning range, a family of four at 100 rather than 150 L per person per day sends away 146 instead of 219 m³ a year — with a 5 m³ tank, about 29 visits instead of 44.

  • Repair a running cistern or dripping tap at once; a leak fills the tank day and night.
  • When replacing a toilet, shower or washing machine, compare the water-use figures in the product data.
  • Keep rainwater, drainage water and groundwater out — they only add cubic metres to haul away.
  • Compare the monthly meter reading with the cubic metres on your emptying receipts; if clearly more is driven away than the meter recorded, water is getting in from elsewhere.

When the rules leave no alternative

The Water Act (Veeseadus) § 124(1) allows three routes: treat wastewater on site, lead it to a treatment plant, or collect it in a holding tank and transport it to a reception point. Which is open to you depends on the address:

  • Collection area of 2000 p.e. or more: own treatment plants (omapuhasti) are prohibited (§ 124(4)). Until public sewerage arrives, a leak-tight holding tank is the lawful solution (§ 124(2)).
  • Collection area below 2000 p.e., no public sewerage: an own treatment plant may be built as well (§ 124(3)).
  • Outside collection areas, no public sewerage: an own treatment plant or leak-tight holding tanks (§ 124(6)).

National law is only the frame: each municipality adopts its own rules for on-site wastewater treatment and removal (reovee kohtkäitluse ja äraveo eeskiri, § 104(7)). Before ordering anything, ask your municipality which area your plot is in and what its rules require. Installation also needs a building notice (ehitusteatis) and later a use notice (kasutusteatis), filed through the Building Register (ehitisregister) at least 10 days in advance (Building Code, Annexes 1 and 2, §§ 36 and 48).

Frequently asked questions

Is a holding tank the right choice for a family living in the house all year? Where the rules leave no alternative, it is the choice — plan the routine above. Where you do have one, be honest about fit: the ministry guide lists holding tanks as suitable where water use is small or periodic, or where the soil or the lack of a recipient for treated effluent rules out on-site treatment. If a treatment system is permitted and feasible on your plot, compare it first, because a holding tank’s cost grows with every litre.

The alarm has gone off and the tanker cannot come for several days. What now? That is what the reserve above the sensor is for. Order at once and cut water use until the visit: postpone laundry, keep showers short. The tank must never overflow. Afterwards, order earlier or have your installer set the sensor lower so the alarm comes sooner.

Should the tank go under the driveway so the tanker can reach it? Better beside it. The ministry guide says a holding tank must not be installed under a road or parking area. Vesmaco’s installation guide permits trafficked areas only with a reinforced-concrete load-distribution slab (at least 15 cm thick, at least 50 cm above the tank, extending 50 cm beyond it on every side) and a suitable EN 124 hatch — work for a qualified designer.

Tell us your household size and we’ll propose volumes. Send the number of people in the house, your monthly water-meter figure if you have one and the largest tanker load available locally through the quote form, or call +372 641 8550. Vesmaco manufactures the tanks, advises on the choice and delivers across Estonia; installation is done by your installer, emptying by your local emptying company or water company.

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