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What Are My Options Regarding An Old Septic Tank On Our Farm?

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"I am considering purchasing a farm in Wales with an old septic tank. What do I need to consider?"

Septic tanks discharging directly to surface water are not permissible and will need to be improved, either by upgrading the treatment system to a small sewage treatment plant or by installing a drainage field and discharging to ground. Discharging sewage directly to groundwater is not permissible. You must use a drainage field located above the water table.

In Wales, a septic tank, small sewage or package treatment plant (the liquid is treated to a level clean enough to flow into a river or stream) must be registered with Natural Resources Wales.

Anyone considering buying a property with a septic tank, or sewage package treatment plant, or cesspit in Wales should satisfy themselves that it:

  • Is in working order
  • Has sufficient capacity to serve the number of occupants of the property
  • Does not cause pollution
  • Complies with any relevant permit, exemption, planning legislation or building regulations
  • Has an easement where any part of the system is on adjoining land, and enforceable rights of access to maintain and replace it
  • Has a written maintenance agreement where any part of the system is on adjoining land and managed jointly with another landowner or by a third party and appropriate cost-sharing provisions

Costs to consider:

  • Upgrading or replacing the septic tank, if it does not meet the standards required under the Environmental Protection Regulations 2016
  • Engaging a surveyor or engineer to inspect the septic tank or sewage system to confirm that it meets the requirements and criteria for any exemption, the quantity of discharge, and any ongoing maintenance inspections or work
  • Applying for an environmental permit if not exempt

If you are buying a property with a septic tank that currently discharges directly to surface water, we suggest you negotiate with the seller as to who will have the responsibility for the replacement or upgrade of the existing sewage system. We suggest you, your agents or your specialist drainage adviser negotiates this for you. We can then put the agreed terms in the sale contract.

You should consult a legal adviser for more detailed guidance.

For more information contact: 03333 208644 or email:

The question posed is based upon a hypothetical situation.