June 2026 – Southern Water have now submitted the Planning Application to the Planning Inspectorate and this page has been refreshed with additional detail.
Environmental concerns are listed in the following content table. Please select the line of interest to move to the appropriate point on the page.
Detrimental impacts on Langstone Harbour
Risks from landfill leachate
Significant risk to Langstone Harbour from building the Water Recycling Plant and large tunnel entry shafts for the 6 pipelines on the contaminated landfill site at Broadmarsh, north of Harts Farm Way in Havant. The Southern Water 2022 Consultation findings confirmed that 41% of respondents did not support the selection of the landfill site at Broadmarsh for the recycling plant, read on to find out why?
The landfill operated from the early 1960’s into the 1980’s dumping industrial, commercial & domestic waste, including incinerator ash, over the harbour muds with no engineering containment below or above the contaminated waste. The waste layer is up to 15m deep
Piling through the contaminated waste for the large number of buildings and tanks needed by Southern Water will open up new pathways into the alluvial silty gravel layer and chalk aquifer below for mobile contaminants (leachate) such as solvents and hydrocarbons.
Risks will be particularly high where the waste has been deposited on top of the historic route of the Hermitage Stream and over old saltmarsh channels and the Southern Water construction works disturb these relic direct pathways to the harbour.
Groundwater in the chalk below the landfill flows to the south and is under tidal influence, any increased risk/flow to the chalk provides a direct route for leachate from the landfill containing contaminants to reach Langstone Harbour.
Southern Water plan to dig at least 3 shafts, each 8 to 12m in diameter, at least 20m deep through the landfill into the chalk to allow them to bore tunnels to carry the 6 pipelines needed for the scheme. This risks opening up significant new migration pathways for contaminated leachate to escape, including along the route of the new tunnel to be constructed below the tidal section of the Hermitage Stream to Budds Farm.
The landfill site at Broadmarsh (Site 72) will need to be levelled to provide a flatter development footprint. This will involve disturbing the cap of the old landfill opening up a number of risks including;
Allowing additional rainwater into the landfill material increasing the risk of leachate generation and migration. This risk would apply for a number of years as the piling blanket placed across the site during construction is likely to be porous.
Introducing oxygen into the landfill material changing the decomposition process within the waste.
Opening up the waste to the air allowing landfill odours to be carried on the prevailing wind towards residential areas to the north.
Any process of damping down to reduce dust generation would add to the water draining into the landfill.
Impact on special interest features of the Special Protection Area (including Brent Geese & waders)
The construction of the Water Recycling Plant and associated shafts/ tunnels will take place adjacent to the harbour muds used by species such as waders, brent geese and gulls. Plus land allocated under the Brent Goose & Wader Strategy. Construction work will be noisy including impact noise which has the potential to disturb the birds. As construction will take place over several years it cannot be timed to avoid the most sensitive times of year.
Note: The environmental impact assessment is also having to consider potential impacts of noise & vibration during construction on fish in Langstone Harbour.
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Visibility impacts around Langstone Harbour
Southern Water have confirmed that the new recycling plant buildings and multiple tanks will be up to 13m high (42ft). Site 72 which has been selected for the plant is on a landfill mound which already rises a significant height above sea level. The northern aspect of Langstone Harbour is dominated by Farlington Marshes and the Broadmarsh Coastal Park giving a fairly rural aspect to views. The new buildings and tanks will be visible from around the coast of Langstone Harbour, adding to urbanisation of views. It will be visible from the NW shore of Hayling Island, Farlington Marshes, Portsea Island, the Millenium Tower & vantage points on Portsdown Hill.
Southern Water have indicated that they will screen the development with additional tree planting, but trees on the landfill regularly die due to exposure of their roots to leachate and landfill gas which displaces oxygen. If you look at the site now trees have not established around the full perimeter of the site 72 leaving gaps.
The Water Recycling Plant is to be lit at night which will add to its visibility from long distances away and impact upon the local night time ecology, such as bats.
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Potential loss of nitrate benefit expected in Langstone Harbour
The original Havant Thicket Reservoir scheme proceeded on the assurance that the use of spring water to fill the reservoir, and top it up after drawdown in a drought, would ensure a reduction in nitrate levels entering the harbour. It is not clear if this benefit will be lost if the operation of the reservoir is altered such that it is kept topped up with recycled water. The water quality modelling being undertaken to assess the impacts of effluent recycling is still ongoing.
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Detrimental impact on the Solent from discharge of concentrated reject water
There is significant concern about the impact of 4x more concentrated reject water from the effluent recycling process being discharged in to the Solent via the existing Eastney Long Sea Outfall. The discharge will include treatment and cleaning chemicals as well as treatment by-products that must be considered. The Southern Water assessment indicates a ‘likely significant effect’ in their Preliminary Environmental Information Report published with the 2024 consultation. Monitoring was ongoing but has not considered all of the contaminants of concern.
The reject water discharged to the Solent is likely to most concentrated in a drought scenario, when the maximum volume of reject water is being produced (20Ml/day), at the same time as the flow of final effluent from Budds Farm to mix with it in the long sea outfall is at its lowest, as 80Ml/day of final effluent is being diverted to the Water Recycling Plant (WRP) for effluent recycling, meaning there will be less waste water from the normal Budds Farm treatment process to dilute the WRP reject water coming out of the Long Sea Outfall.
Note: There is also the potential for the additional solid waste from the Water Recycling Plant to be put back into the Budds Farm works, if this is to be the case the impacts of this also need to be considered in the modelling for the revised discharges for the Long Sea Outfall.
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Huge energy & chemical use, even when there is not a drought
Effluent recycling was proposed primarily as a drought resource, yet Southern Water have indicated that they will operate the plant and pipelines at a capacity of 30 million litres every day. Think of the huge amount of treatment chemicals and energy that will be needed to treat and pump what is 12 Olympic sized swimming pools of water everyday 40km to Otterbourne, even when it is raining and we have plenty of water.
Note: To keep the treatment plant and pipelines in operational order Southern Water must operate the plant and pipelines at a minimum flow of 30Ml/day (12 Olympic size swimming pools).
Southern Water have confirmed that the effluent recycling treatment plant alone will use energy at a rate of 0.95kWh/m3, with the additional water treatment still needed at the Otterbourne works taking 0.457kWh/m3 (1m3 = 1000 litres and they plan to treat 30 million litres per day). The energy consumption and cost of treatment for the recycled water are therefore 3 times higher than that of conventional river water treatment.
That does not include the costs to pump the recycled water 4km to Havant Thicket Reservoir, nor the cost to pump the mixed water 40km to Otterbourne, which must be huge, given a 90m vertical height rise just to the top of Portsdown Hill. Southern Water have previously said they cannot provide the energy figures for pumping water along the pipelines. Given that the daily energy cost of water pumping will be extremely high how have they determined that this is a ‘best value’ solution for their customers without this information.
Note: Southern Water committed to customers and local councillors that they would provide more information on the energy requirements of the proposals at the 2024 consultation, but no additional information has been provided. In a Gate 3 report to Ofwat Southern Water that the water transfer would cost more than £4 million, with the cost to treat and transfer the recycle effluent costing will be more than £13 million pounds per year, in a non-drought year, with much higher costs in a drought year.
Energy security is already a significant concern in the UK, selecting and developing high energy solutions to meet our water supply needs will just add to the national & regional problems, and those of the planet.
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Enormous carbon impact during construction and operation
The carbon impact to construct the effluent recycling plant & associated chemical tanks, reject water tanks, sub-station and other structures will be large. Add to that the need for 3 new pumping stations at Havant, 3 pumping stations & 2 break pressure tanks along the pipeline route, with 6 new pipelines needed, including a 40km+ pipeline to Otterbourne, the resultant carbon footprint for construction of the scheme alone is enormous. Then add on the carbon footprint to operate the treatment plant and pipelines 365 days a year.
The water industry is committed to being carbon neutral by 2030 and Southern Water has signed up to delivering this. This plant is scheduled to open in 2035, how can Southern Water ever hope to meet its commitment to being carbon neutral if it does not start planning now to deliver more sustainable solutions that work with climate change instead of against it.
Yet the selection of effluent recycling via Havant Thicket and transfer (40km) to Otterbourne results in unacceptably high carbon impact and greenhouse gas emissions, more than double that of any other transfer or desalination scheme. In fact, the SW restricted documents confirm that the Hampshire effluent recycling/ transfer scheme has a higher total carbon, average carbon emissions & embedded carbon impact than sea tankering water in from Norway!
Given the huge energy requirement for both treatment and transfer of recycled effluent, it is difficult to see how this can possibly be considered a ‘best value’ solution for customers, or for the environment given the huge annual carbon impacts.
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Environmental impacts on Havant Thicket Reservoir
Increased risk of pollution to the reservoir
The risk of pollution to the reservoir is currently extremely small, with the catchment to the north limited to just the Havant Thicket woodland area. There is a significant concern that there will be an increased risk of pollution from the recycling plant if Southern Water do not adequately maintain the treatment plant to prevent pollution incidents. Southern Water will be in control of the complex new plant and its maintenance including that of the analysers which will test the quality of the water. Once in, pollution cannot be removed from the reservoir.
The treatment process cannot remove 100% of all potential contaminants. Small quantities of pollutants such as pharmaceuticals, pesticides and PFAS forever chemicals can pass through the treatment process and will be discharged into the reservoir daily. The percentage of removal will depend on the contaminant. The risk of bioaccumulation also needs to be considered, especially for PFAS compounds which do not degrade in the environment.
While Portsmouth Water have said they will be able to shutdown the pipeline to the reservoir if there is any concern about water quality, they will be relying on data provided by the Southern Water analysers, often monitoring surrogate parameters rather than actual contaminants. There will be no independent constant monitoring of the discharges into the reservoir. Most of the complex chemicals that would be of concern cannot be monitored in real time, instead samples collected would take up to 28 days to analyse in a laboratory, by the time the results come back any pollution would already be in the reservoir.
The Reverse Osmosis treatment process is very complex, requires a fairly consistent treatment stream, highly trained & competent operators, and a lot of maintenance which is expensive. The final effluent stream pumped from Budds Farm will vary, for example, as a result of storm water dilution effects through the treatment works. Given Southern Water’s track record locally with coastal discharges, poor maintenance, telemetry failures, more than £90 million in recent fines, the company are not trusted to run this technology which is new to the UK for public water supply. Add to that £126 million in penalties for the manipulation and misrepresentation of regulatory data the concerns mount. While it may be technically possible with a well run plant to treat the effluent to meet drinking water standards after dilution in the reservoir, people are concerned that Southern Water will not run the plant 100% effectively all of the time, especially when they know the water is going into an ‘environmental buffer lake’ (the reservoir) and not direct into the drinking water supply.
A local manufacture who installed Reverse Osmosis (RO) to treat their waste stream has told us that it was so very difficult to operate, including problems with the membranes degrading making the plant really expensive to operate. In the end they decided it was just not practical and cost effective to operate the RO treatment plant and they stopped using it.
We have heard that the RO treatment plant which Thames Water use for desalination is “more often broken than working, the maintenance is intensive and requires specialists”.
Can we trust Southern Water to operate this complex plant safely and without causing pollution to the reservoir or the Solent?
Changes to temperature, salinity and loss of a unique opportunity to create a chalk spring fed reservoir
Havant Thicket Reservoir would be the first chalk spring fed reservoir in the world. Creating a truly unique biodiversity opportunity in Hampshire. Adding warmer recycled effluent to the reservoir which has a different geochemistry will fundamentally change the composition of the water in the reservoir and potentially alter the ecology. Southern Water have previously confirmed they have no plans to remineralise the recycled water to that of a calcareous water similar to the springs water which was to have filled the reservoir.
The sewage entering the Budds Farm WWTW is adversely affected by saline intrusion. The pressure that the Reverse Osmosis plant will operate at will not be enough to remove all of the salt from the recycled water. Higher salinity recycled water entering the reservoir could have a significant impact on reservoir water quality and biodiversity.
Impact of rapid changes in water composition
In a drought Southern Water plan to pump into the reservoir 60Ml/day of recycled effluent and take out 90Ml/day. This will result in rapid changes to the geochemistry of the water. The impacts of this are not yet fully understood as the water quality modelling work is ongoing.
Everyday of the year 30Ml/day of recycled effluent will be discharged into the reservoir, with the same volume of mixed water being removed and pumped to Otterbourne. The composition of the water in the reservoir will slowly change through time. It is important that water quality under all of the reservoir operating regimes is fully modelled and published so that the impacts of the discharges into the reservoir can be fully understood, as well as the implications for downstream water courses. For example, will it reduce or increase the risk of algal blooms? which can have a significant adverse effect on the ecology of the reservoir.
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Risk of turning people away from tap water & creating a plastic bottle waste mountain
Effluent recycling runs the risk of turning consumers away from tap water, due to the lack of trust in Southern Water, who have recent history of significant treatment failures. Southern Water have confirmed that mixed reservoir water (containing recycled water) is likely to taste different to the water consumers are used to drinking. Large numbers of people have said they will reject the recycled water and turn to bottled water with all the adverse environmental impacts that brings (plastic manufacture, transport of heavy bottles, bottle waste and so on). This is something that has already happened in California & Singapore where recycled water is already used. In Singapore as many as 70% of customers use bottled water and there is now a huge recycling problem. Adopting effluent recycling could result in unacceptably high use of bottled water, creating a new plastic waste problem.
It is a retrograde step to risk driving people away from tap water to bottled water, with knock on economic and potential health impacts for the poorest in our society.
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Adverse environmental impacts associated with plant & pipeline construction
a) You cannot build a 40km+ pipeline through the Hampshire countryside from Havant to Otterbourne without there being adverse impacts on habitats and wildlife during tunnel shaft and open cut construction. While the direct impacts will be for 1 to 2 years, it will take many years for habitats to recover, leaving a scar on the landscape for years to come.
b) Landfill gas could be mobilised along tunnel, pipeline and other utility corridors. Great care will be needed to ensure that the risk of gas migration away from the Broadmarsh landfill are fully considered and controlled for the life of the development and after demolition.
c) The pipeline construction requires the construction of temporary ponds to take discharge/ washout water. Control measures will need to be put in place to minimise the risk of pollution to local water courses, including at the 4 major river crossings and associated tributaries.
d) Details of permanent washouts and where they will discharge is not yet known. This is a particular concern where the pipelines will carry final effluent from Budds Farm sewage works, reject water from the Water Recycling Plant, and treated effluent to Bedhampton springs and mixed water to the Havant Thicket Reservoir.
e) Tunnelling below the Hermitage Stream to install 2 pipes from the Budds Farm sewage works to the Water Recycling Plant brings with it the risk of mobilising leachate from the landfill, pollution from construction, and pollution if there are future bursts of the pipes carrying final sewage effluent & concentrated reject water.
f) Noise and light pollution from permanent above ground plant along the pipeline routes during construction and operation. Control measures will need to put in place to minimise the impacts.
g) Significant impact during construction on historic conservation areas including Old Bedhampton. There will be a significant impact during construction on historic conservation areas including Old Bedhampton, with construction traffic for the new shafts, tunnels and pipelines entering the old village to access Mill Lane. Plus the potential for the second reservoir pipeline option to be open cut through the historic parkland at Staunton Country Park.
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Effluent recycling is not a sustainable solution
Especially when the proposal is to build the treatment plant 40km from where the water is actually needed in Southampton & Winchester. Greener options need to be prioritised for investigation. Recent winters have shown that we get plenty of rainfall, we need to find solutions that work with climate change, not against it. Collecting and storing the rainwater could have additional benefits in terms of reducing flood risk. For more information on alternatives click here. (add link to alternatives text)
More environmentally friendly alternatives have been parked by Southern Water instead of being brought forward for investigation.
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Environmental assessment undertaken was not robust
The screening undertaken to enable selection of effluent recycling was at too high a level to understand the risks. How does the scheme which had the most negative impacts get selected? (The Hampshire & Littlehampton effluent recycling schemes had the highest negative environmental impact scores we found in the short time Southern Water made available to view the restricted environmental assessment report at their Worthing HQ)
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Effluent recycling should fail a robust Habitats Regulation Assessment
Any robust assessment of the impacts of the effluent recycling scheme on the local European Protected Sites should demonstrate a ‘likely significant effect’. There is a concern that by the time a full Habitats Regulation Assessment has been completed, Southern Water will have pushed the regulators into a corner and argue that it is too late to develop alternatives and there is an over-riding public need for the effluent recycling. This is because Southern Water are not developing a plan B, they paused work on an alternative option utilising Peel Common sewage works in May 2023. The Preliminary Environmental Information Report (2024) has confirmed a ‘likely significant effect on the protected sites in the Solent. Modelling undertaken subsequently has not considered all of the contaminants of concern.
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No proposal to improve discharge consents on industrial discharges into the sewers
The Budds Farm sewage works receives sewage from a broad catchment covering Portsmouth, Havant and many industrial estates beyond. Southern Water has confirmed that it has no plans to improve controls on discharges into the sewers from industrial and commercial operators. Instead, they intend to rely solely on the treatment process to remove contaminants of concern. Good practice guidance from drought stricken countries using effluent recycling to create drinking water emphasises the importance of improving controls and monitoring in the sewer catchment.
Why are Southern Water not proposing to improve controls and monitoring in the sewer catchment?
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[Last updated, 26/2/2026]