ILLUSTRATIVE PROJECT • HOMEOWNER GUIDE
Planning a septic tank
and drainage field replacement.
See how an installation could progress from the first investigation to the finished groundworks, and what to ask before agreeing a quotation.
This is a fictional planning example, not a completed Prime Drainage job. The credited reference photographs show separate third-party installations.
THE EXAMPLE SCENARIO
An older system.
A recurring problem.
Imagine a rural home with an older septic tank and recurring wet ground near the suspected drainage field. The owner wants to understand the cause, the options and the disruption before committing to work.
For this example, assume that investigation and testing support a replacement tank and a suitable new drainage field. A real property could need a different solution, including repairs, further investigation or another treatment arrangement.
There is no assumed tank size, trench length, price or completion time. Those decisions follow the property assessment and agreed scope.
UNDERSTAND THE WHOLE SYSTEM
The tank and the outlet work together.
- House drainageWastewater travels through the connecting drains.
- Septic tankSolids settle and the liquid effluent flows onward.
- Drainage fieldA suitable infiltration system disperses effluent into the ground for further treatment.
A sewage drainage field and a rainwater soakaway have different purposes. This example concerns sewage from a septic tank. For roof or surface-water problems, see our rainwater soakaway service.
FROM INVESTIGATION TO HANDOVER
How this example could progress.
Investigate the existing system
For this example, the first visit would establish what the tank serves, where the outlet goes and what can be inspected. Accessible connecting drains may need CCTV. Wet ground alone would not establish that both the tank and drainage field need replacing.
Check whether the proposed solution is suitable
The next stage would consider property use, soil and percolation testing, groundwater, available space, access and nearby features. The applicable permissions and discharge requirements would need checking before the system and layout are agreed.
Agree a written quotation
If the findings supported replacement, the quotation would identify the selected tank, drainage field, connecting pipework, excavation, spoil handling and reinstatement. Any specialist emptying, removal of the old tank, approvals and additional works should be clearly allocated and priced.
Prepare the site and install
Once the design, permissions and scope were resolved, the work could move to service checks, safe excavation, tank positioning and the drainage field. Installation details would follow the agreed design and relevant manufacturer instructions.
Check connections and reinstate
The agreed checks would cover the installed connections, access points and drainage route. The quotation should say how excavated ground, lawns or other surfaces will be finished, and which areas are included.
Hand over the records
The handover should explain the installed system, access locations and maintenance responsibilities, with the agreed photographs, checks and product information. Any outstanding items should be recorded clearly.
BEFORE YOU ACCEPT A QUOTE
Know what the finished job includes.
- Which findings support the proposed work?
- What testing, design and permissions are included or still needed?
- Who arranges specialist emptying and disposal, if required?
- What access, excavation and spoil removal are allowed for?
- Which connections, checks and surface repairs are included?
- What records and maintenance information will be handed over?
The intended result in this example would be an agreed replacement system, checked connections, reinstated areas and clear handover records. It is a planning objective, not a reported customer outcome.
Planning work in England
A site-specific assessment should establish the applicable general binding rules, any environmental permit requirements, and the planning or building approvals needed. A septic tank must not discharge directly to a watercourse.
Environment Agency: discharge to ground · Discharge to surface water
Guidance checked 18 October 2026. The photographs illustrate equipment and groundwork; they are not a construction specification or an endorsement of Prime by the photographers or people shown.
SPEAK TO PRIME DRAINAGE
Planning a septic or drainage field project?
Send your postcode, the existing system and any symptoms, reports or access details. Prime serves Gloucestershire, Worcestershire, Herefordshire and the Cotswolds and can discuss the appropriate assessment and quotation.