Introduction

When a property is situated in a remote location, such as a long distance from the nearest village or on a small island, it is often unfeasable to connect this property to the main sewage network. More often than not the reason is simply down to the large cost of creating a sewage system for a single property.

In these instances, the waste water from the property is collected in either a cesspool or a septic tank.

Cesspools

By far the most expensive option in the long term, a cesspool is a simple collection point for waste water from a property.

Located below ground level, a cesspool requires emptying anything from every week to once a month depending on the water usage of the property. The emptying process of cesspools is often a service provided by local councils, especially in rural areas, and specialist firms which have the necessary tankers.

• Your Local Council

Traditionally, cesspools are cylindrical pits dug in the grounds of the property, and lined with bricks. Modern versions are either concrete lined or a prefabricated Glass Reinforced Plastic (GRP) container which is lowered into the hole.

• The building regulations stipulate that cesspools must have a minimum capacity of 18 cuM (4000 gallons).

• Before purchasing a property with a cesspool, enquire as to the exact volume of the container to ensure that it can accomodate your families needs. As a guide, an average person uses 115 litres of water per day.

Septic tanks

Unlike a cesspool, a septic tank actually treats the waste water as well as collecting it. The waste from the property flows into the chamber, where bacteria breaks down and digests the waste. The treated water is discharged through a network of pipes into the soil of the garden.

The area beneath the garden which contains the discharge pipes is called a 'leaching field'.

• Sewage water in the tank seperates slowly, with the heavier sludge falling to the bottom of the tank, and the lighter waste forming a scum on the surface.
• Incoming waste water to the chamber enters below the scum layer to avoid disturbing the sewage treatment process.
• The bacterial action within the tank takes a minimum of 24 hours to treat the water, to prevent the waste flowing too quickly the tank contains baffles which slow the movement.
• The partly treated water flows through the main tank into a network of piping and drains which disperse the water over a wide area, called the 'leaching field', to filter through the soil.
• If the garden of the property isn't of sufficient size to accomodate the piping required, the waste water can instead flow into a secondary chamber containing a deep bed of gravel to allow further bacterial action to take place.

• Septic tanks are often not suitable for properties with heavy clay soil gardens as the water cannot disperse adequately within the leaching field.

If your property is built on a heavy clay soil layer then the most suitable option is a cesspool. Likewise if you have a small garden a cesspool may be a better option than a septic tank.

What to watch out for

• Nearly all problems associated with cesspools and septic tanks are related to the size of the device.

When dealing with modern properties, the chances are that the cesspool or septic tank is of a size to accomodate the needs of most families, however if the property was built before the late 1970s then there is a high probability that it will not be large enough for modern living.

Washing machines, dishwashers, power showers, etc all increase the water consumption of the property considerably, so with this in mind either ensure the existing facility is large enough or make provisions for the installation of a new one.

It's not unheard off for owners of properties with a small cesspool or septic tank to install a submerged pump to prematurely expel water straight out of the tank into a nearby ditch or land drain.

• It is illegal to discharge untreated water as there is a high probability that it will pollute the water course.

• A standard installation of a cesspool or septic tank is at least £2,000, it is worth bearing this cost in mind when considering purchasing a property that may/may not require a new installation.

Further information and useful links

• Mains water systems
• Drainage systems
• Advice for clearing blocked pipes & drains
• More plumbing & heating topics

• Find a Drainage Specialist near you