No Mains Drainage? Your Options

Most UK properties, particularly those in urban areas, are connected to a gravity-fed main sewer system for the removal of waste and foul water from toilets, bathrooms, kitchens and laundries. If your property is within 30 metres of a main sewer, the Environment Agency will generally expect you to connect to it, even if this incurs high costs or challenges.

However, many rural areas don’t have nearby main sewers and even in some urban areas, wastewater treatment plants may already be working to full capacity and cannot support another property. And wherever it is located, if your property sits below the level of a main sewer a gravity feed system won’t work. In these cases, off-main drainage may be the only option. 

Let’s look at three ways in which wastewater can be managed without a main connection.

Pumping wastewater – pumping stations

If your property is more than 30 metres from or sits below the level of a gravity drain, a pumping station may be one of the best options: while the cost and maintenance of the pumping station remain the responsibility of the property owner, the main sewer system and wastewater treatment are managed by the local authority.

A pumping station is comprised of a large tank to temporarily hold sewage until it reaches a certain level in the tank. At this point, the sewage pump automatically kicks in and forces the wastewater along the connection to the main sewer. In some instances, a macerator fitted to the pump chops solid effluent into a semi-liquid state to make pumping easier and reduce the risk of blockages.

If you decide to install a pumping station there are a few points you need to consider:

Requirements

Your choice of pumping station will be determined by several factors. 

• How far will it need to pump horizontally (the distance in a flat line between the pump and the main sewer) and vertically (the difference in elevation between the two points)?
• What type of property (single dwelling, multiple dwellings, commercial building, etc.) and how many people (occupants, visitors, etc.) will the pumping station be serving?
• What will be the approximate flow rate (litres per minute) into the system from the property?
• What storage capacity will be needed in the event of a 24-hour power outage?

Costs

A pumping station system must be designed and installed by professionals, which can add to the initial costs. The installation is also likely to involve public road works, with connection fees, road closures and traffic management adding to the cost. 

Ongoing operational costs will include energy usage for the pump and regular servicing and maintenance.

Permissions

You will need approval from the local authority or sewerage provider to connect to the main sewer. If the route of the connection between your pumping station and the main sewer passes over land belonging to a third party (such as a neighbour), you will need written permission from them. This may require some form of legal advice or involvement, which will also add to your costs.

Compliance

Any wastewater pumping system must comply with BS 756-2 and Building Regulations for Foul Drainage.

Storing wastewater - cesspits

Wastewater storage systems have been used for centuries, but the holding tanks of today are substantially safer for the environment than the cesspits of our predecessors.

Although they are now illegal in Scotland, effluent holding tanks (also still referred to as cesspits) provide sewage management at its most basic level. Sewage is simply held in the tank until it is emptied by an effluent removal tanker but as the sewage isn’t treated (which reduces its water content), a larger tank will be needed and emptying must be carried out more frequently.

If you think wastewater storage is your best option you will need to consider the following:

Requirements

For a domestic property, you should allow a minimum storage capacity of 18,000 litres for a two-person household plus 6,800 litres for each additional person. For non-domestic use, we strongly advise consulting an expert to establish the appropriate tank capacity.

Costs

An effluent holding tank is a reasonably basic piece of equipment with no power requirement and few moving parts. However, its larger capacity will add installation costs as a larger, deeper pit will need to be excavated to contain it.

Ongoing costs are the highest for all off-main options as the tank must be regularly emptied by a registered waste carrier.

Permissions

To install a new cesspit, you will need to follow guidelines issued by the Environment Agency and obtain planning permission from your local authority.

Compliance

Cesspit installations must comply with Building Regulations, which include allowing a minimum gap of 7 metres between the tank and the foundations of any building and 2 metres from any boundary.

Treating wastewater – septic tanks

The most popular option for off-main sewage management is to treat the wastewater, either with a septic tank or sewage treatment plant. With both methods extracting liquid effluent from the sewage, this reduces the volume of sewage to be emptied from the tank and therefore how frequently this is required.

A septic tank is similar to a cesspit, with one difference: it uses gravity to separate any liquid effluent from the solids and discharges this liquid into the soil via a soakaway or drainage field. The sludge this leaves behind is then removed by a registered waste carrier.

As the liquid effluent percolates into the soil of the soakaway or drainage field, bacteria that are naturally present in the soil break it down to make it safe for humans and the environment.

Septic tanks have been in use for a long time, but have fallen out of favour more recently due to concerns about environmental pollution.

If you are considering installing a septic tank, bear in mind the following:

Requirements

Septic tanks offer restricted capacity and can only serve a property with a limited number of occupants, while a drainage field requires plenty of undeveloped space to discharge the effluent over a large area. 

A soakaway has a smaller footprint than a drainage field but has an average lifespan of 10-25 years. Once this has expired, a new soakaway in an entirely new location must be excavated. If properly installed and maintained, a drainage field can last up to 50 years.

Soakaways and drainage fields must both be installed in soil which offers good drainage and a low water table, but as soil type can vary significantly even within a small area, this can be a challenge.

Costs

The installation costs of a septic tank would be higher than those of a cesspit as they include the additional purchase and installation costs of a soakaway or drainage field.

The operational costs of a septic tank are lower than those of a cesspit as emptying the tank is required less frequently. However, if a soakaway is installed the costs of replacing this should be built into the long-term operational costs.

Permissions

Septic tanks are not permitted in Zone 1 of a Groundwater Source Protection Zone. Permission may however be granted in other zones in certain situations.

Compliance

Under new environmental legislation, a septic tank may no longer discharge directly into a watercourse such as a ditch or stream. Discharge into a soakaway or drainage field must comply with BS 6297 and Building Regulations, which include allowing a minimum gap of 7 metres between the tank and the foundations of any building and 2 metres from any boundary.

Treating wastewater – sewage treatment plants

Concerns about environmental pollution have led to a rise in the popularity of sewage treatment plants. While these are similar in many ways to septic tanks, they use a multi-chamber system and air pumps to break down the effluent so that the treated liquid is clean enough to discharge into waterways.

The first stage in a sewage treatment plant is to separate the solid and liquid effluent. Air pumped through the effluent then introduces oxygen to encourage aerobic bacteria growth; this digests some of the solid waste and breaks down nitrates in the liquid effluent. By the end of this process, the sewage treatment plant has produced a liquid that can be safely released into the environment and a much-reduced sludge to be emptied from the tank less frequently than any other off-main sewage system.

If you think that a sewage treatment plant is the best option for your property, consider the following points:

Requirements

Sewage treatment plants are available in a wide range of sizes that accommodate a higher number of users. They require a suitable electrical connection to power the air pumps.

Fats, greases and non-degradable items such as sanitary products should never be flushed down sinks or toilets, regardless of what sewage management system they are connected to, but this is especially important with sewage treatment plants as they can interfere with the bacterial process. Likewise, care should be taken in the cleaning chemicals used in the bathroom, kitchen and laundry as bleach-based and other cleaning products that aren’t bio-friendly will kill off the helpful bacteria.

Costs

Sewage treatment plants cost more to install than other off-main wastewater systems and require regular servicing and maintenance to keep them running efficiently and prevent premature failure of moving parts. They also incur a minimal cost for the electricity required to power the pumps.

However, these costs are offset in the long run by the fact that a sewage treatment plant requires emptying much less frequently than any other system.

Permissions

Planning permission is needed to install a sewage treatment plant. 

If you want to discharge directly into a ditch, stream or other watercourse, you will require consent from the Environment Agency. If consent isn’t granted or there is no nearby watercourse to discharge into, a sewage treatment plant can be connected to a drainage field. Due to the treatment process, a smaller drainage field will be required than for a septic tank of a similar capacity (up to 20% smaller) and as the discharge is cleaner the lifespan of the drainage field will be much longer.

Compliance

Sewage treatment plants must comply with Building Regulations and meet EA General Binding Rules.

We hope this information will help you determine which off-main wastewater system is best for you and your property. If you have any further questions you are always welcome to call our friendly team of experts on 01420 555600 or email [email protected].

Also, look out for more articles in our ongoing series of blog posts, bringing you useful information, insights, guides and tips on all things drainage!