Is It a Problem to Buy a House With a Septic Tank?

Buying a house with a septic tank is not automatically a problem. Many rural, semi-rural and larger properties rely on private drainage because they are not connected to the public sewer. A well-installed and properly maintained septic tank or sewage treatment plant can serve a property perfectly well. The problem is uncertainty. When you buy the property, you may also be taking on responsibility for an underground drainage system that you cannot fully assess just by walking around the house. You need to know what type of system is installed, where it is located, where it discharges, whether it has been maintained and whether it appears to meet the relevant rules. That is why a septic tank should not simply be treated as a minor detail in the property purchase.

What Should You Check Before Buying a House With a Septic Tank?

Before exchange, it is sensible to establish the basics of the private drainage system. You should try to find out:

• Whether the property has a septic tank, sewage treatment plant, cesspit or another form of private drainage
• Where the tank or treatment plant is located
• Where the drainage field, soakaway or discharge point is located
• Whether the system serves only the property you are buying or is shared with other properties
• How old the system is
• Whether it has been emptied and maintained regularly
• Whether service records, emptying records or installation documents are available
• Whether there have been previous problems, repairs or alterations
• Whether the system appears to comply with the General Binding Rules
• Whether replacement, repair or further investigation may be needed

A specialist septic tank homebuyer survey can help answer these questions before you commit to the purchase.

Why a Standard Building Survey May Not Be Enough

A standard building survey looks at the condition of the property, but it may not provide a detailed assessment of the off-mains drainage system. Private drainage is a specialist area. A septic tank, sewage treatment plant or drainage field may be underground, partly hidden, difficult to access or poorly documented. In some cases, even the seller may not fully understand how the system works. A building surveyor may identify that the property has private drainage, but that is not the same as assessing the condition, discharge arrangements or compliance position of the system. This is particularly important where the property is rural, older, extended, has land, includes outbuildings or appears to have a drainage system that has changed over time.

Is the System a Septic Tank, Sewage Treatment Plant or Cesspit?

The first question is what type of system the property actually has. The terms are sometimes used loosely during property sales, but they do not all mean the same thing. A septic tank separates solids from wastewater and normally discharges liquid effluent to the ground through a suitable drainage field. A sewage treatment plant treats wastewater to a higher standard, often using mechanical components, and may be suitable for different discharge arrangements depending on the site and permissions. A cesspit or cesspool is a sealed holding tank. It does not discharge treated effluent and needs regular emptying. Knowing which system serves the property matters because each type has different maintenance, compliance and cost implications.

Where Does the Septic Tank Discharge?

This is one of the most important questions when buying a property with a septic tank. The system may discharge:

• To the ground through a drainage field
• To a sewage treatment plant and then to an approved outlet
• To a ditch, stream, river or other watercourse
• To an arrangement that is unclear or undocumented

A septic tank itself should not discharge directly into surface water such as a ditch, stream, river or watercourse. Older rural properties may have arrangements that have existed for many years, but that does not automatically mean they meet current expectations. If the discharge point is unclear, unsuitable or difficult to confirm, this should be investigated before exchange rather than discovered after completion. Boxall Ward can carry out an off-mains drainage compliance check where there is uncertainty about the system or its discharge.

Does the Septic Tank Comply With the General Binding Rules?

The General Binding Rules apply to qualifying small sewage discharges from septic tanks and sewage treatment plants in England. If you are buying a property with off-mains drainage, you need to know whether the system appears to meet the relevant requirements. This can include questions such as:

• Is the correct type of treatment system installed?
• Where does the system discharge?
• Is there evidence of pollution?
• Is the system properly maintained?
• Is the system correctly sized for the property?
• Is the drainage field suitable and functioning?
• Are there protected sites, watercourses or other sensitive features nearby?
• Are permits, permissions or further checks needed?

For more background, see Boxall Ward’s guide to General Binding Rules and property sales.

What Paperwork Should the Seller Provide?

When a property with a private sewage discharge is sold, written information about the system should be provided to the new operator. Useful information may include:

• A description of the treatment and drainage system
• The location of the main parts of the system
• The location of the discharge point
• Details of any alterations to the system
• Maintenance requirements
• The manufacturer’s manual, where available
• Service records, where available
• Emptying or desludging records
• Any permits, consents, installation documents or previous reports

Missing paperwork does not always mean there is a major problem. However, it does mean you may need to rely more heavily on a specialist inspection rather than assuming everything is in order.

Who Becomes Responsible After Completion?

Once you buy the property, you may become responsible for the septic tank, sewage treatment plant or private drainage system serving it. This responsibility can include operation, maintenance, emptying, repair and ensuring that the system does not cause pollution. If the system is shared with other properties, responsibility may be shared as well. That does not automatically tell you how maintenance or repair costs are divided. Those legal and financial arrangements may depend on title documents, deeds, easements, maintenance agreements or other arrangements. If the system is shared, read who is responsible for a shared septic tank. Your solicitor or conveyancer should check the legal responsibilities attached to the property. A drainage specialist can assess the physical condition and apparent compliance of the system.

Could Septic Tank Problems Delay a Property Purchase?

Yes, septic tank issues can delay a property purchase, especially if they are discovered late. Potential problems include:

• Unclear discharge arrangements
• A septic tank discharging directly into a watercourse
• No maintenance records
• Signs of system failure
• A damaged tank or failed drainage field
• A shared system with unclear legal responsibilities
• A system that may need upgrading or replacing
• Disagreement between buyer and seller about who should pay for remedial work

Finding an issue does not automatically mean the sale has to fall through. In many cases, the important thing is to understand the position clearly so the buyer, seller and solicitor can decide how to proceed.

What Are the Warning Signs of Septic Tank Problems?

Some drainage problems are visible before purchase, although others may only become clear during inspection. Warning signs can include:

• Slow drains or toilets that do not clear properly
• Sewage smells inside or outside the property
• Wet, boggy or unusually green patches of ground near the drainage field
• Sewage appearing at ground level
• Standing water around inspection covers
• Repeated blockages
• Treatment plant alarms
• Poor access for emptying or maintenance
• Unclear pipework or undocumented alterations
• A seller who cannot explain where the system discharges

These signs do not always prove that the system needs replacing, but they do mean further investigation is sensible. Early assessment can help prevent a manageable issue becoming an expensive surprise after completion.

Should You Arrange a Septic Tank Survey Before Exchange?

In most cases, yes. If you are buying a property with septic tank, sewage treatment plant or cesspit drainage, a specialist survey can provide valuable information before you exchange contracts. A septic tank homebuyer survey may help establish:

• What type of system serves the property
• Where the tank or treatment plant is located
• The apparent condition of the visible components
• Whether there are signs of damage, blockage or failure
• Where the system appears to discharge
• Whether the drainage field can be identified
• Whether the system appears to have been maintained
• Whether there are potential General Binding Rules concerns
• Whether repair, replacement or further investigation may be needed

For a more detailed explanation, read what happens during a septic tank homebuyer survey.

What If the Septic Tank Needs Repair or Replacement?

If a problem is found, the next step depends on the nature of the issue. Possible recommendations may include:

• Emptying and cleaning the tank
• Repairing damaged pipework
• Servicing or repairing a sewage treatment plant
• Replacing damaged components
• Investigating an unknown discharge point
• Replacing a failed drainage field
• Installing a compliant drainage field
• Upgrading from a septic tank to a sewage treatment plant
• Applying for an environmental permit where required
• Connecting to the public sewer where this is reasonable and available

The important point is that decisions should be based on evidence, not guesswork. A survey can help establish whether the issue is minor, manageable, urgent or likely to involve significant replacement work. For more detail, see what a septic tank compliance inspection checks.

Can the Buyer and Seller Agree Who Pays?

Where a septic tank or sewage treatment system needs work, the buyer and seller may need to agree how that issue is dealt with as part of the transaction. This might involve the seller arranging work before completion, the buyer proceeding with an agreed allowance, or the parties agreeing another practical solution through their solicitors. Boxall Ward cannot provide legal advice on the terms of a property sale. However, a specialist inspection can provide the technical information needed so the buyer, seller, estate agent and conveyancer can understand the drainage issue more clearly.

The Bottom Line

Buying a house with a septic tank is not automatically a problem, but it should never be ignored. Before you exchange contracts, you should understand what type of private drainage system serves the property, where it is located, where it discharges, whether it has been maintained and whether there are signs of non-compliance or failure. A specialist septic tank homebuyer survey can help identify problems before they become your responsibility. Boxall Ward carries out septic tank surveys, off-mains drainage inspections and compliance checks for buyers, sellers, estate agents and conveyancers across Sussex, Surrey, Hampshire, Kent, the New Forest and selected Thames Valley areas. Call 01903 815377 or contact Boxall Ward to discuss a septic tank survey before buying a property.

Frequently Asked Questions