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    Sewage Treatment Plants

    At KD Drainage, we are specialists in the installation of all types of foul drainage systems, including sewage treatment plants throughout London and Kent, providing homeowners and businesses with a complete installation and maintenance service. With over 20 years of experience, we have established ourselves as a leading installer of all pumps including septic tanks and sewage treatment plants, so you know you can count on us. KD Drainage work alongside all commercial and domestic customers to design and install a sewage treatment plant system that meets your budget and site requirements.

    Ground conditions can vary dependent on the location of a household or business, that’s why at KD Drainage we install various makes of sewage treatment plants from a range of brands.

    All sewage treatment plant installations work is carried out in accordance with the Environment Agency Regulations and Section H2 of Building Regulations.

    What is a Sewage Treatment Plant?

    A sewage treatment plant is a stand-alone sewage treatment system that works underground.

    A sewage treatment plant treats wastewater entering a pit and then discharges it to either a local water course or a man-made soakaway. The location of a sewage treatment plant is dependent on EA requirements.

    Sewage treatment plants are mainly found in rural areas where no main drainage system exists and are generally more cost-efficient to install than traditional main sewage systems. This is because the sewage water is treated onsite within the sewage treatment plant. This reduces the need to install sewer lines that connect a household or building to the main sewage system, cutting costs.

    Our Services Include

    • Commercial consultancy and installation of sewage treatment plants
    • Commercial maintenance and repairs of sewage treatment plants
    • Domestic/household installation of sewage treatment plants
    • Domestic/household servicing and repairs of sewage treatment plants

    How is a Sewage Treatment Plant Installed?

    Before a sewage plant is quoted, our specialist engineers at KD Drainage will carry out some necessary research such as the quantity of people, and number of bedrooms, using the sewage treatment plant. We will then recommend the best possible option for the property’s requirements.

    The correct location of the sewage treatment plant is then marked out and the excavation will be carried out using specialist machinery, such as an excavator. The pump station is installed at the required depth and the associated pipework is then connected. The tank will then be filled with water to allow for external backfill or concrete, depending on the manufacturers’ recommendations.

    Once the backfill is complete, the outlet pipework is excavated to either a nearby water course or a herringbone drainage field. A percolation test will later be required to determine the VP rate for discharge purposes. We then make the connection to the electrical supply and carry out a full test of the installation.

    On completion of all installations, we will issue a warranty for workmanship, manufacturer's warranty, and recommendations for further servicing.

    Unlike septic tanks, sewage treatment plants treat the sewage so that it is suitable to be discharged to ditches and streams and comply with Environment Agency guidelines.

    All sewage treatment plants will be inspected by our trained specialist engineers prior to being approved for installation. The sewage treatment plant is delivered to your site by us, to ensure the plant is delivered at a time that suits you best, with no delays.

    All our engineers are specialists in handling and installing all makes and models of sewage treatment plants. At KD Drainage, customer safety is our top priority. That’s why care is always taken during both the delivery and installation of any sewage treatment plant ensuring that damage to both our clients’ property and the sewage treatment plant is minimised.

    Why Do I Need a Sewage Treatment Plant?

    Many households or commercial businesses, particularly in rural areas, may not be connected to the mains sewage systems. With access to clean water becoming trickier to access due to various reasons including increased water demand and pollution, homeowners and business need to ensure that they have a safe and dependable alternative.

    Difference Between Sewage Treatment Plants & Septic Tanks

    Septic Tanks

    Septic tanks are the most common underground solution when a property is not connected to the mains and are sometimes considered as ‘private drainage’. Septic tanks can process and discharge the sewage that is collects, unlike a cesspool which only stores the sewage and must be manually emptied regularly. Septic tanks use gravity to separate the liquid waste from the solid waste, however a high quantity of this solid waste will remain within the tank and will therefore build up over a period of time. This means that this will need emptying at regular intervals by a registered waste carrier.

    Lighter solids in wastewater such as oils and grease float to the surface of the water whereas heavier solids float to the bottom. These liquids flow out of the tank into a soakaway, also known as a drainage field, and is safely disposed of into the surrounding soil. This causes waste-degrading bacteria to break down any remaining waste.

    Sewage Treatment Plants

    Put simply, sewage treatment plants are a further evolution of the septic tank and essentially do the same thing by separating liquid waste from solid and transporting this into the soakaway. However, the main difference is that they make the wastewater cleaner and less harmful.

    Once this wastewater has entered the holding chamber of the tank and gravity has separated the liquids from the solids, the liquids flow into a second chamber. The solids are left in the first chamber to later be cleared by a registered waste carrier. Oxygen is then pumped into the system using an air pump to encourage the waste-degrading (or aerobic) bacteria to break down the leftover sewage into cleaner wastewater. This now becomes a type of bacteria-infused liquid and flows into the last chamber where the bacteria settles to the bottom. This bacterium is later recycled back into the first chamber to start the process again, and the cleaner sewage is discharged either into a soakaway or directly into a direct watercourse or ditch, since this wastewater is cleaner than that of a septic tank. Where this is discharged however is subject to consent by the local environment authority.

    Sewage Treatment Plants vs Septic Tanks

    • Septic tanks work under a ‘two step’ process, whereas sewage treatment plants typically work using a ‘three step’ process.
    • Sewage treatment plants have mechanical components that require a permanent source of electricity to work, however this is not the case with septic tanks.
    • A sewage treatment plants separates and treats the wastewater, whereas a septic tank simply separates this, thus, water leaving a sewage treatment plant is a lot cleaner than that leaving a septic tank.
    • As discussed, treated wastewater from a sewage treatment plant can be directly discharged into a local watercourse, unlike wastewater from a septic tank.

    Important Note: as of 2020 it is illegal to have a septic tank that discharges wastewater to a local watercourse. This must be discharged to a soakaway or drainage field. If you own or are selling a property, the septic tank system must be upgraded.

    Here at KD Drainage all our engineers hold the industry leading NADC accreditation to ensure every client has a concise, professional and trustworthy Home Buyers Drainage Survey to give you the peace of mind you deserve when buying your new home.

    KD Drainage also install Septic Tanks for both commercial and domestic customers, to view more about our services, click here.

    Benefits of a Sewage Treatment Plant

    There are multiple benefits to sewage treatment plants:

    1. Reduces Health Risks

    Sewage treatment plants can often treat sewage wastewater to a higher standard than septic tanks. This reduces health risks to humans, the environment and animals as untreated wastewater can carry life-threatening diseases. Therefore, installing a sewage treatment plant to ensure that sewage is being treated and disposed of in a safe and environmentally friendly manner.

    2. Minimal Odour

    Modern wastewater systems such as sewage treatment plant installations release minimal odour from sewage or wastewater, unlike earlier and older systems.

    3. Simple & Safe Installation

    Our engineering specialists at KD Drainage have the capabilities to safely install sewage treatment plants to both commercial and domestic customers throughout the UK and Kent. In some instances, installing a sewage treatment plant can be more beneficial than installing a septic tank as the treated sewage water can be legally disposed of into surface waters, whereas the wastewater from septic tanks must be removed annually.

    4. Cost Effective & Reliable

    Sewage treatment plant installations require very little maintenance and do not waste as much water as main line sewers. Installing a sewage treatment plant is more reliable and cost-efficient, eco-friendly and easy to maintain in the long run.


    Due to the sophisticated, reliable and efficient sewage treatment plant installations carried out by our specialist engineers at KD Drainage, this process does have few limitations:

    Yearly Servicing and Maintenance

    Whilst sewage treatment plants need emptying less than septic tanks, the build-up of solid waste in the first chamber of the tank, must be emptied typically once a year. Furthermore, due to the existence of mechanical parts, a sewage treatment plant will require regular maintenance and servicing by our team to ensure that this does not break down and continue to work effectively throughout the year.

    Electrical Connection

    To install the air pump to pump oxygen into the system, the sewage treatment plant requires an electrical connection and so can sometimes incur further operational costs.

    Higher Initial Cost

    A sewage treatment plant costs more initially compared to a septic tank. Extra costs are also incurred if there is no direct and natural watercourse, soak-away or drainage field for the waste water to be directed to.

    Contact Us

    If you wish to know more about sewage treatment plant installations throughout London and Kent, call us today on 01622 919012 to speak to one of our specialists directly, or fill out the form below.

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