The scheme for 68 homes in Barns Green near Horsham had already been met with strong objections from residents concerned about its impact on local infrastructure, wildlife and the rural character of the village.
The situation has not been improved by claims that Southern Water may close nearby Itchingfield Wastewater Treatment Works (WTW) and divert flows to the Barns Green site.
In a letter to a local resident seen by The Argus, the water provider asks permission to assess their land’s suitability for a pipeline diverting flows from Itchingfield to Barns Green.
The letter also said the Barns Green facility had the capacity to cope with the additional load.
It reads: “Barns Green is a newer and larger works, with the capacity not only to receive the additional flows but also to accommodate the treatment processes to improve the quality of treatment over and above that currently at Itchingfield.”
However, residents argue that repeated failures at the Barns Green facility, especially during storms, highlight longstanding shortcomings in the area’s infrastructure.
Photographs attached to one objection letter received by the council appear to show raw sewage leaking from a manhole into nearby beauty spot Parsons Brook.
Campaigners are calling on Horsham District Council to reject or delay the plan.
Richard French, chairman of a local campaign group, said: “This changes everything.
“Barns Green’s wastewater infrastructure is already at breaking point.
“To approve further large-scale development in this context would be reckless.”
Mr French said: “It’s about whether the basic infrastructure exists to support this development.
“The answer, clearly, is that it does not.
“Proving the capacity to deal with the intended level of sewage is surely an essential requirement of any application.
“We don’t want our country lanes running with sewage.”
Campaigners are calling on the council to ensure the Southern Water proposal is fully assessed before a decision on the planning application is made.
A Miller Homes spokesman said: “Southern Water confirmed to Horsham District Council in January 2026 that there is adequate capacity within the local sewerage network to serve our proposed scheme in Barns Green, and they reaffirmed in April 2026 that the situation hasn’t changed.
“While residents have expressed concerns, these are not reflected in Southern Water’s consultation responses. As such, we are satisfied that the proposed development can be safely accommodated by the existing sewerage network.”
When The Argus put residents’ concerns to Southern Water, a spokesman said: “Housing matters at local councils are not something that Southern Water can comment on.
“We are not statutory consultees on planning applications and developers have a right to connect to our network when plans are approved by local authorities.
“Water companies have statutory obligations to provide water and wastewater services, we cannot refuse new connections and we are unable to object to new developments.
“While no plans are currently in place, the Itchingfield WTW and flows to the Barns Green facility are under consideration.”
Horsham District Council is accepting feedback from the public via its online planning portal, which can be given by quoting planning reference DC/25/2057 until July 2.