Sewage Treatment System Costs in Hampshire & Surrey
By Alton Facility Services • Reviewed by Senior Pump Engineer • Updated June 2026
Sewage treatment system costs vary depending on the system type, site conditions, discharge method and groundworks required.
A low-cost option is not always the best long-term solution if it creates compliance or maintenance problems.
This guide explains typical cost factors for Hampshire and Surrey properties.
Quick Answer
Typical septic tank installations may range from around £3,000 to £7,000, while sewage treatment plants often range from around £6,000 to £15,000+ depending on site conditions.
Running costs, servicing, emptying and repairs should also be considered.
Septic Tank Installation Costs
Septic tanks are usually cheaper upfront because they have fewer mechanical components.
Costs can rise if a new drainage field, difficult excavation or access work is required.
Sewage Treatment Plant Costs
Treatment plants usually cost more because they use a more advanced treatment process with mechanical and electrical components.
They may be better value long term where compliance or watercourse discharge is important.
Running Costs
Most treatment plants require electricity, usually for aeration or pumping components.
Modern systems are designed to be efficient, but electricity should still be allowed for in lifetime costs.
Servicing Costs
Annual servicing is recommended for sewage treatment plants to check pumps, blowers, controls and treatment performance.
Our maintenance guide explains what should be checked.
Emptying Costs
Both septic tanks and treatment plants need periodic emptying to remove sludge.
Frequency depends on system type, usage and tank size, but many domestic systems need emptying every one to two years.
Hidden Cost Factors
Costs can increase because of poor access, deep excavation, tree roots, clay soil, groundwater, proximity to buildings or the need for pumping equipment.
A site survey is the safest way to avoid surprises.
Repair or Replace?
Older systems with compliance issues can become expensive to maintain.
If faults are recurring, read signs your sewage system needs replacing.
Get a Tailored Quote
Alton Facility Services can assess your site and recommend a suitable system based on compliance, access and long-term value.
Need a costed proposal? Contact our team or call 0808 175 5779.
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