A new grant is being developed to help homeowners upgrade older septic tanks to modern Package Treatment Plants. These upgraded systems help protect our rivers, improve local water quality and support precious wildlife across the River Itchen catchment and the Solent.
This guide explains:
Our aim is to make the process clear, friendly, and easy to follow and are still finalising the exact way in which you apply so some minor changes to the information below might happen before the application process is launched.
Protecting our rivers and wildlife
The Solent and its rivers — including the Itchen, Test, Meon, Hamble and the New Forest streams — are internationally important for wildlife. Thousands of resident and migrating birds depend on these waterways, along with iconic species like otters, water voles and salmon.
However, nutrient pollution is harming these sensitive habitats. Older septic tanks can release nutrient rich rich wastewater into rivers, causing algal blooms which:
Upgrading your septic tank helps stop this pollution, protecting our rivers for generations to come.
Who is behind the grant?
In 2024, councils across Hampshire joined forces to create the Solent Mitigation Partnership (SMP). The SMP is funded by central government and supported by 16 local authorities, including Winchester City Council, and operates under the umbrella of the Partnership for South Hampshire.
The SMP works closely with environmental partners on our projects and in consultation with Natural England, and other stakeholders such as Southern Water and Portsmouth Water.
Examples of our project partners are
Up to £30,000 grant to upgrade your septic tank
The SMP will cover the cost of replacing your existing septic tank with a modern Package Treatment Plant. This usually includes:
The only costs you may need to pay are:
Choose your own installer
Unlike other schemes, you can choose your own installer. You may pick from installers already registered with the SMP or nominate your preferred contractor.
The legal agreement
To make sure the environmental benefits are long-term, the grant requires you to sign a Unilateral Undertaking (UU). This ensures:
In return, the nutrient credits created by your upgrade are transferred to the SMP to support environmentally responsible housing delivery across Hampshire.
You can apply if:
If you are unsure whether you qualify, the SMP team can help you check.
What you’ll need
Before starting your application, gather:
If you are missing information, the team can help you find it.
The application process (5 simple steps)
Step 1: Apply online
Fill out our online application form. You will receive an application reference number, which our team will use to verify any contact with you.
Applications will open in the Summer 2026.
Step 2: Pre-acceptance acceptance checks
The SMP checks:
Step 3: Site visit and Technical Report
Your chosen installer visits your property to:
Step 4: Grant decision
On the first Wednesday of each month we will assess all the quotes and technical report that have been received. We will select those that are successful and by the 2nd Wednesday of the month inform you of our decision. Do not begin any works until approval is confirmed.
Step 5: Installation
If approved, you:
The full process typically takes around six months.
Contracting with your installer
You will enter a contract directly with your chosen installer. A pre start meeting is recommended to agree:
During installation
Your installer will need to:
They will advise you on any preparation needed.
Completion pack
You will receive:
Servicing and maintenance
To keep your system running efficiently:
Nutrient credits
By accepting the grant, you transfer the nutrient credits created by your upgrade to the SMP. These help unlock new housing without harming protected habitats.
Issues and complaints
If something goes wrong:
1. Contact your installer first
2. Contact the SMP team if you need further help
To reduce nutrient pollution from older septic tanks and protect sensitive wildlife habitats in the Solent and River Itchen catchment.
The grant is funded by central government and delivered by the Solent Mitigation Partnership, a collaboration of 16 local authorities and environmental organisations.
If you live in the Itchen catchment, own a residential property (Council Tax band A–D) and have a septic tank over 10 years old, you may qualify.
Up to £30,000, covering the system, installation, survey and first year year servicing.
No — you choose your own installer.
You will need to pay for the electricity to run the system, annual servicing and eventual future replacement. There might also be optional extras you request from the installer that will be at your cost.
To ensure the environmental benefits last 100 years and that nutrient credits can be transferred to the SMP.
The agreement must be shared with future buyers but should not prevent a sale.
Approximately six months from application to installation.
Planning fees are covered by the grant. The SMP and your installer will support you.
Yes — the SMP team can guide you through every step.
You can still apply. Your installer will assess the situation.
Your installer first — then the SMP team if needed.
No — these transfer to the SMP in exchange for your fully funded upgrade.
Most domestic systems operate at a noise level of 35-55 decibels (dB) when measured from a distance of one meter, which is comparable to a quiet conversation or a refrigerator running. This will not be noticeable in most locations, but if the tank if situated close to where you spend time, this may be a consideration to talk to the installer about.
Smaller domestic systems typically use around 0.6 kWh per day (about the same as a light bulb).
We’re here to support you at every stage.
📧 SMPGrant@fareham.gov.uk