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Septic tanks: What are they and how do they work?
<p>If your property cannot connect to the mains sewerage system, a septic tank may be the most practical solution for managing wastewater.</p> <p>In this guide, we'll cover everything you need to know about how septic tanks work, including what parts make up a septic tank system, how often they need to be emptied, and how they treat wastewater.</p> <p><a href="https://www.forwardbs.co.uk/civils/treatment-tanks/">Explore our range of septic treatment tanks</a></p> <p><strong>Contents:</strong></p> <ul class="wp-block-list"> <li><a href="#what-is-a-septic-tank">What is a septic tank?</a></li> <li><a href="#who-needs-a-septic-tank">Who needs a septic tank?</a></li> <li><a href="#what-parts-make-up-a-septic-tank-system">What parts make up a septic tank system?</a></li> <li><a href="#how-does-a-septic-tank-work-in-the-uk">How does a septic tank work in the UK?</a></li> <li><a href="#what-happens-to-the-solid-waste-in-a-septic-tank">What happens to the solid waste in a septic tank?</a></li> <li><a href="#how-often-does-a-septic-tank-need-to-be-emptied">How often does a septic tank need to be emptied?</a></li> <li><a href="#what-can-and-cant-go-into-a-septic-tank">What can and can't go into a septic tank?</a></li> <li><a href="#are-septic-tanks-environmentally-friendly">Are septic tanks environmentally friendly?</a></li> <li><a href="#septic-treatment-tanks-from-forward-builders-supplies">Septic treatment tanks from Forward Builders' Supplies</a></li> </ul> <h2 class="wp-block-heading" id="what-is-a-septic-tank">What is a septic tank?</h2> <p>Septic treatment tanks are large, underground containers used to treat wastewater from toilets, sinks, baths, and showers.</p> <p>They provide a convenient solution for properties that cannot reasonably connect to the mains sewerage system, allowing them to manage their wastewater independently.</p> <p>The wastewater is partially treated inside the tank before the resulting effluent is safely discharged into a suitable drainage field.</p> <p>Septic tanks are heavily regulated in England, so anyone who owns a property with a septic tank must ensure their system meets the government's 'general binding rules'. These help to protect the environment and public health from hazardous, untreated wastewater.</p> <p>In some circumstances, it used to be possible to discharge a septic tank directly into a watercourse like a stream, river, or ditch.</p> <p>However, since regulations changed in 2020, you're no longer allowed to do this.</p> <h2 class="wp-block-heading" id="who-needs-a-septic-tank">Who needs a septic tank?</h2> <p>UK Building Regulations state that all buildings should connect to the mains sewer if it's reasonable for them to do so.</p> <p>However, where this is not possible, septic tanks offer a practical solution for wastewater management.</p> <p>Septic tanks are most often used by:</p> <ul class="wp-block-list"> <li>Homeowners living in rural locations</li> <li>Isolated community buildings</li> <li>Remote businesses like country pubs and farm shops</li> </ul> <h2 class="wp-block-heading" id="what-parts-make-up-a-septic-tank-system">What parts make up a septic tank system?</h2> <p>Before we explain how a septic tank works, it's useful to understand all the different parts that make up a septic tank system and what they're for.</p> <figure class="wp-block-table"><table><thead><tr><th>Component</th><th>What does it do?</th></tr></thead><tbody><tr><td>Septic treatment tank</td><td>The large underground container that wastewater flows into</td></tr><tr><td>Inlet pipe</td><td>Carries the wastewater from the property to the septic tank</td></tr><tr><td>Outlet pipe</td><td>Carries partially treated effluent out of the tank and directs it to the drainage field</td></tr><tr><td>Vent</td><td>Allows gases produced in the tank to escape</td></tr><tr><td>Effluent filter</td><td>Prevents solids from leaving the septic tank and clogging the drainage field</td></tr><tr><td>Access risers and lids</td><td>Provide access to the tank for inspections, maintenance, and emptying</td></tr><tr><td>Drainage field</td><td>Consists of a network of perforated pipes buried under gravel. It receives partially treated wastewater from your septic tank for further natural treatment</td></tr></tbody></table></figure> <h2 class="wp-block-heading" id="how-does-a-septic-tank-work-in-the-uk">How does a septic tank work in the UK?</h2> <p>A septic tank doesn't just store wastewater; it treats it and then safely disperses it out into a drainage field.</p> <p>Here's what happens at each stage of the process:</p> <h3 class="wp-block-heading">Step 1: Wastewater enters the septic tank</h3> <p>Wastewater from a property's toilets, sinks, baths, and showers flows through the inlet pipe and into the septic tank.</p> <h3 class="wp-block-heading">Step 2: The wastewater separates into three layers</h3> <p>Once inside the tank, over time, the wastewater separates into three layers:</p> <ul class="wp-block-list"> <li><strong>Top layer:</strong> oils, fats, and grease float to the top and form a scum</li> <li><strong>Middle layer:</strong> Liquid wastewater floats in the middle</li> <li><strong>Bottom layer:</strong> Solid waste sinks to the bottom and forms a sludge</li> </ul> <h3 class="wp-block-heading">Step 3: Bacteria break down the organic waste</h3> <p>Anaerobic bacteria (bacteria that don't need oxygen) break down some of the organic matter in the sludge and wastewater using a process called anaerobic digestion.</p> <p>This helps to reduce the volume of solid waste inside the tank.</p> <h3 class="wp-block-heading">Step 4: Partially treated effluent leaves the tank</h3> <p>Partially treated wastewater passes through the effluent filter and exits the tank via the outlet pipe.</p> <h3 class="wp-block-heading">Step 5: The effluent enters the drainage field</h3> <p>The effluent then enters the drainage field through a network of perforated pipes. This ensures that it is spread out across the field, rather than flooding out at one single point.</p> <h3 class="wp-block-heading">Step 6: The soil provides further treatment</h3> <p>The wastewater then percolates through a layer of gravel and into the soil beneath, where microorganisms provide further filtration and treatment before the water disperses into the ground.</p> <h2 class="wp-block-heading" id="what-happens-to-the-solid-waste-in-a-septic-tank">What happens to the solid waste in a septic tank?</h2> <p>Solid waste sinks to the bottom of the tank and forms a layer of sludge. Some of this solid waste breaks down, but not all of it.</p> <p>The waste that remains gradually builds and must be removed periodically.</p> <h2 class="wp-block-heading" id="how-often-does-a-septic-tank-need-to-be-emptied">How often does a septic tank need to be emptied?</h2> <p>Typically, most septic tanks need to be emptied about once a year, but this can vary depending on the size of your septic tank and how many people live or work in the property it is attached to.</p> <p>The tank should only ever be emptied by a professional and specialist company.</p> <p>The process involves inserting a long flexible tube into the tank and then sucking the sludge out directly into a tanker, which then takes it away and disposes of it safely.</p> <p>It's essential to ensure the tank is emptied regularly, or you could run into serious problems.</p> <p>If the tank fills up with too much sludge, you could find the wrong type of waste flowing out into your drainage field, or even backing up into your property.</p> <p>Not only will this cause some pretty unpleasant smells, but it could also be hazardous to both your health and the environment.</p> <h2 class="wp-block-heading" id="what-can-and-cant-go-into-a-septic-tank">What can and can't go into a septic tank?</h2> <p>It's extra important to be careful about what you put down the toilet or wash down the sink if your property has a septic tank.</p> <p>Using the wrong products, or flushing something that you shouldn't, could block the pipes or your tank, or harm the beneficial bacteria that help to break down and treat the wastewater.</p> <p>A septic tank that isn't functioning properly poses a health and safety risk and could contaminate the environment around it.</p> <p>Here's a quick guide to what can and can't go into a septic tank:</p> <h3 class="wp-block-heading">What can safely go into a septic tank?</h3> <ul class="wp-block-list"> <li><strong>Septic-safe cleaning products:</strong> It's best to choose one septic tank-safe, biodegradable cleaning product and stick to it. This helps to protect the bacteria in your system</li> <li><strong>Natural human waste:</strong> Flushed down the toilet</li> <li><strong>Toilet paper:</strong> Look for fast-dissolving, biodegradable tissue paper, preferably single-ply</li> <li><strong>Wastewater:</strong> Grey wastewater from showers, baths, basins, and sinks</li> </ul> <h3 class="wp-block-heading">What should not go into a septic tank?</h3> <p>The short answer to this question is: anything not listed above!</p> <p>Items that people often mistakenly put in that can cause a septic tank to malfunction or prevent it from performing at its best include:</p> <ul class="wp-block-list"> <li>Sanitary products, wet wipes, and nappies</li> <li>Harsh cleaning products and chemicals</li> <li>Fats, oils, and grease</li> <li>Rainwater</li> <li>Medicines</li> <li>Food waste</li> </ul> <h2 class="wp-block-heading" id="are-septic-tanks-environmentally-friendly">Are septic tanks environmentally friendly?</h2> <p>Yes, a septic tank that is being used and maintained correctly is an environmentally friendly solution for treating wastewater.</p> <p>Septic tanks use naturally occurring bacteria to break down waste and treat water rather than harsh chemicals, and most tanks require little or no energy to operate.</p> <h2 class="wp-block-heading" id="septic-treatment-tanks-from-forward-builders-supplies">Septic treatment tanks from Forward Builders' Supplies</h2> <p>Ready to buy a septic treatment tank and start your project?</p> <p>At Forward Builders' Supplies, we stock a wide range of septic tanks, from small 4-person tanks to large 10-person tanks.</p> <p>All our products are manufactured by leading septic tank brands, like Marsh Industries, to ensure long-lasting, reliable performance.</p> <p>We also offer free delivery to customers located within 50 miles of our depot in Ellesmere Port, Cheshire.</p> <p>If you need help selecting the right septic tank for your property, contact us on 0151 357 1035, and we'll be happy to help.</p> <p>Or, for help installing a septic tank, read our guide to <a href="https://www.forwardbs.co.uk/blog/everything-you-need-to-know-about-septic-tank-installation/">everything you need to know about septic tank installation</a>.</p>
If your property cannot connect to the mains sewerage system, a septic tank may be the most practical solution for managing wastewater.
In this guide, we'll cover everything you need to know about how septic tanks work, including what parts make up a septic tank system, how often they need to be emptied, and how they treat wastewater.
Explore our range of septic treatment tanks
Contents:
- What is a septic tank?
- Who needs a septic tank?
- What parts make up a septic tank system?
- How does a septic tank work in the UK?
- What happens to the solid waste in a septic tank?
- How often does a septic tank need to be emptied?
- What can and can't go into a septic tank?
- Are septic tanks environmentally friendly?
- Septic treatment tanks from Forward Builders' Supplies
What is a septic tank?
Septic treatment tanks are large, underground containers used to treat wastewater from toilets, sinks, baths, and showers.
They provide a convenient solution for properties that cannot reasonably connect to the mains sewerage system, allowing them to manage their wastewater independently.
The wastewater is partially treated inside the tank before the resulting effluent is safely discharged into a suitable drainage field.
Septic tanks are heavily regulated in England, so anyone who owns a property with a septic tank must ensure their system meets the government's 'general binding rules'. These help to protect the environment and public health from hazardous, untreated wastewater.
In some circumstances, it used to be possible to discharge a septic tank directly into a watercourse like a stream, river, or ditch.
However, since regulations changed in 2020, you're no longer allowed to do this.
Who needs a septic tank?
UK Building Regulations state that all buildings should connect to the mains sewer if it's reasonable for them to do so.
However, where this is not possible, septic tanks offer a practical solution for wastewater management.
Septic tanks are most often used by:
- Homeowners living in rural locations
- Isolated community buildings
- Remote businesses like country pubs and farm shops
What parts make up a septic tank system?
Before we explain how a septic tank works, it's useful to understand all the different parts that make up a septic tank system and what they're for.
| Component | What does it do? |
|---|---|
| Septic treatment tank | The large underground container that wastewater flows into |
| Inlet pipe | Carries the wastewater from the property to the septic tank |
| Outlet pipe | Carries partially treated effluent out of the tank and directs it to the drainage field |
| Vent | Allows gases produced in the tank to escape |
| Effluent filter | Prevents solids from leaving the septic tank and clogging the drainage field |
| Access risers and lids | Provide access to the tank for inspections, maintenance, and emptying |
| Drainage field | Consists of a network of perforated pipes buried under gravel. It receives partially treated wastewater from your septic tank for further natural treatment |
How does a septic tank work in the UK?
A septic tank doesn't just store wastewater; it treats it and then safely disperses it out into a drainage field.
Here's what happens at each stage of the process:
Step 1: Wastewater enters the septic tank
Wastewater from a property's toilets, sinks, baths, and showers flows through the inlet pipe and into the septic tank.
Step 2: The wastewater separates into three layers
Once inside the tank, over time, the wastewater separates into three layers:
- Top layer: oils, fats, and grease float to the top and form a scum
- Middle layer: Liquid wastewater floats in the middle
- Bottom layer: Solid waste sinks to the bottom and forms a sludge
Step 3: Bacteria break down the organic waste
Anaerobic bacteria (bacteria that don't need oxygen) break down some of the organic matter in the sludge and wastewater using a process called anaerobic digestion.
This helps to reduce the volume of solid waste inside the tank.
Step 4: Partially treated effluent leaves the tank
Partially treated wastewater passes through the effluent filter and exits the tank via the outlet pipe.
Step 5: The effluent enters the drainage field
The effluent then enters the drainage field through a network of perforated pipes. This ensures that it is spread out across the field, rather than flooding out at one single point.
Step 6: The soil provides further treatment
The wastewater then percolates through a layer of gravel and into the soil beneath, where microorganisms provide further filtration and treatment before the water disperses into the ground.
What happens to the solid waste in a septic tank?
Solid waste sinks to the bottom of the tank and forms a layer of sludge. Some of this solid waste breaks down, but not all of it.
The waste that remains gradually builds and must be removed periodically.
How often does a septic tank need to be emptied?
Typically, most septic tanks need to be emptied about once a year, but this can vary depending on the size of your septic tank and how many people live or work in the property it is attached to.
The tank should only ever be emptied by a professional and specialist company.
The process involves inserting a long flexible tube into the tank and then sucking the sludge out directly into a tanker, which then takes it away and disposes of it safely.
It's essential to ensure the tank is emptied regularly, or you could run into serious problems.
If the tank fills up with too much sludge, you could find the wrong type of waste flowing out into your drainage field, or even backing up into your property.
Not only will this cause some pretty unpleasant smells, but it could also be hazardous to both your health and the environment.
What can and can't go into a septic tank?
It's extra important to be careful about what you put down the toilet or wash down the sink if your property has a septic tank.
Using the wrong products, or flushing something that you shouldn't, could block the pipes or your tank, or harm the beneficial bacteria that help to break down and treat the wastewater.
A septic tank that isn't functioning properly poses a health and safety risk and could contaminate the environment around it.
Here's a quick guide to what can and can't go into a septic tank:
What can safely go into a septic tank?
- Septic-safe cleaning products: It's best to choose one septic tank-safe, biodegradable cleaning product and stick to it. This helps to protect the bacteria in your system
- Natural human waste: Flushed down the toilet
- Toilet paper: Look for fast-dissolving, biodegradable tissue paper, preferably single-ply
- Wastewater: Grey wastewater from showers, baths, basins, and sinks
What should not go into a septic tank?
The short answer to this question is: anything not listed above!
Items that people often mistakenly put in that can cause a septic tank to malfunction or prevent it from performing at its best include:
- Sanitary products, wet wipes, and nappies
- Harsh cleaning products and chemicals
- Fats, oils, and grease
- Rainwater
- Medicines
- Food waste
Are septic tanks environmentally friendly?
Yes, a septic tank that is being used and maintained correctly is an environmentally friendly solution for treating wastewater.
Septic tanks use naturally occurring bacteria to break down waste and treat water rather than harsh chemicals, and most tanks require little or no energy to operate.
Septic treatment tanks from Forward Builders' Supplies
Ready to buy a septic treatment tank and start your project?
At Forward Builders' Supplies, we stock a wide range of septic tanks, from small 4-person tanks to large 10-person tanks.
All our products are manufactured by leading septic tank brands, like Marsh Industries, to ensure long-lasting, reliable performance.
We also offer free delivery to customers located within 50 miles of our depot in Ellesmere Port, Cheshire.
If you need help selecting the right septic tank for your property, contact us on 0151 357 1035, and we'll be happy to help.
Or, for help installing a septic tank, read our guide to everything you need to know about septic tank installation.
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