Septic tank or treatment plant: how to choose and buy without mistakes
Capacity and number of residents
A septic tank is chosen not by the area of the house but by the number of people and daily water use. Permanent living needs a bigger capacity than a weekend home that you visit now and then. Seasonal use also affects the type of plant: some biological plants do not like long breaks. So in your request be sure to write how many people live there and how often.
Septic tank, treatment plant or holding tank
- Septic tank — treats the sewage only partly and needs further treatment (a soak pit, drainage field); it can be plastic or made of concrete rings.
- Treatment plant — cleans the water more deeply with bacteria and needs electricity and servicing.
- Holding tank — just collects the sewage, which must be taken away regularly; it suits as a temporary option.
Soil and groundwater decide everything
The way of installing, and even the choice of type, depends on the soil. In clay soil water is absorbed poorly, so a soak pit will work worse. A high water table can push a light plastic tank up, so it is fixed to a slab. Before ordering, find out the water level on the plot and the type of soil, and also the distance from a well, the house and the plot boundaries: local rules apply there, and it is better to check them in advance with specialists. In flood-prone areas and in the rainy season, ask the installer how the tank is protected against floating.
What to put in your request
- What you need — septic tank, treatment plant, holding tank, soak pit.
- Number of residents — for example 4 people.
- Permanent or seasonal — weekend home or permanent living.
- Soil and water — clay, sand, high groundwater.
- Capacity — in m³ or litres, if you know it.
- Make and model — if you have a preference.
- Installation — digging, fitting, connection, drainage.
- Address and budget.
Example: “I need a treatment plant for a house where 4 people live permanently; the soil is clay and the groundwater is high. I need turnkey installation including digging. Central, budget up to HK$9,400.”
How it works on BlaBlaPrice
Septic tanks and plants are sold by both makers and dealers, and installation is done by separate crews. Instead of looking for each one separately, you write one request, and sellers answer in the chat: the model, price, what installation includes, timing. Each seller sees where their offer ranks and can improve the terms. The best offer is shown first, with the seller's reviews next to it. Your phone stays hidden until you choose a seller. More in how it works.
How to compare offers
Compare for the same number of people and the same type of soil. Ask whether the price includes earthworks, pipes, manholes, the soak pit, electricity, start-up and training. For a plant, find out the electricity use, how often it is serviced and the cost of consumables. A typical mistake is to choose too small a capacity “to be cheaper” and then have to empty it more often.
For the work on the plot you may need plumbing, electrical supplies to power the plant, and steel products and rebar for the slab under the tank.
