Guildford drainage guide
Off-mains drainage around Guildford
Practical guidance for septic tanks, sewage treatment plants, cesspits and private wastewater systems serving properties without a direct mains sewer connection.
Published 2 January 2026
What off-mains drainage includes
Private wastewater systems can include septic tanks, sewage treatment plants, cesspits, pumping chambers and drainage fields. The right approach depends on the installed system, how the property is used, the discharge route and the condition of the connecting drainage.
Understand the existing system
A septic tank separates solids and allows effluent to leave through a suitable drainage field. A treatment plant uses additional treatment stages before discharge. The correct maintenance and discharge requirements depend on the installed system and site.
Planning installation or replacement
The work needs to consider occupancy, ground conditions, access, discharge route, electrical requirements and the applicable approval process. A new system should not be selected on tank size alone.
Routine servicing and emptying
Follow the manufacturer’s servicing schedule and arrange emptying at an interval that reflects the system, occupancy and measured accumulation. Keep service and waste-transfer records with the property information.
Warning signs to investigate
Slow drainage, odour, alarms, unusual pump operation, ponding near the discharge area or backing up can indicate a fault. Reduce water use where appropriate and arrange inspection before the problem worsens.
Information that helps us plan the work
Tell us the property location, system type if known, occupancy, last service or emptying date, any alarm shown and where odour, backing up or ponding is occurring. Photographs of accessible equipment labels and previous service records can also help without replacing an on-site assessment.