Letter from Simon Thackray to North Yorkshire Council re Planning Application ZB25/01465/OUT for 484 houses in Northallerton.
The Northallerton sewerage system has no available capacity to treat additional foul waste from any new development. It doesn’t have the capacity to treat the sewage from the existing population. Northallerton and Romanby Sewage Treatment Works (STW) is in breach of regulation 4(4) of the Urban Waste Water Treatment Regulations. The STW spilled raw sewage into the local watercourse on 104 occasions in 2024, for a total of 500+ hours. A copy of my email sent to the Local Planning Authority is below.
[OFFICIAL – SENSITIVE]
FAO North Yorkshire Planning Control,
Re Application ZB25/01465/OUT
Land To Rear Of Winton Road Northallerton North Yorkshire.
Proposal: Outline planning application (all matters reserved except access) for a phased residential-led development comprising up to 484 dwellings (including up to 0.9ha retirement living (Use Class C2 and/ or Use Class C3)), neighbourhood centre (comprising Use Class C3 with Use Class E, F2, Sui Generis, and maximum of 200 sqm per retail unit (Use Class E)), a one form entry primary school (no less than 1.5 hectares (Use Class F1), landscaping, drainage, access and other associated infrastructure.
In its letter of 28 July 2022 re Application Reference 20/01687/OUT (Northallerton), Yorkshire Water stated:
“The public foul network within the vicinity of the site does not have adequate capacity available to accommodate the anticipated foul water discharge from the proposed development.”
Evidence of inadequate capacity in the Northallerton public foul sewer network is contained in the Environment Agency Event Duration Monitoring (EA EDM) records for the years 2021, 2022, 2023 and 2024. This information is freely available and shows the Northallerton and Romanby Sewage Treatment Works (STW) spilling raw sewage into Willow Beck, a tributary of the River Wiske, and polluting the local aquatic environment
(There are several other combined sewer overflows (CSOs) operating in Northallerton in addition to the sewage treatment works, and ALL are spilling raw sewage into the local watercourse).
The Ofwat permitted number of sewage spills (per CSO) to 2030 is 20 per annum reducing to 10 spills per annum by 2035.
The EA EDM records for Northallerton and Romanby STW below reveal the magnitude of the problem facing Yorkshire Water and the Local Planning Authority:
2021
Sewage spills: 167
Duration of spills: 2034.8 hours
Long term average spill count: n/a
2022
Sewage spills: 118
Duration of spills: 599.7 hours
Long term average spill count: 144.7
2023
Sewage spills: 92
Duration of spills: 464.50 hours
Long term average spill count: 131.50
2024
Sewage spills: 104
Duration of spills: 505:30:00 hours
Long term average spill count: 126.00
EDM data is published on both the Yorkshire Water and Environment Agency websites:
https://www.yorkshirewater.com/environment/storm-overflows/event-duration-monitoring/
https://www.data.gov.uk/dataset/19f6064d-7356-466f-844e-d20ea10ae9fd/event-duration-monitoring-storm-overflows-annual-returns
As stated by Yorkshire Water in July 2022, the Northallerton public foul sewer network does not have adequate capacity to treat the volume of sewage produced by the existing population of Northallerton, let alone the added volume that would be generated by a growth in population. The evidence presented in the EA EDM records for the Northallerton and Romanby STW, and the Yorkshire Water Section 19 Undertakings to Ofwat (of March 2025) is conclusive. The Northallerton sewerage system has NO available capacity to accommodate any new development at this time.
YWS has confirmed that an investigation will be undertaken within the next 5 years and that the outputs of that investigation will inform their investment plans submitted to OFWAT as part of the PR29 regulatory submission. The March 2025 ‘Notice of Ofwat’s decision to accept Section 19 undertakings from Yorkshire Water’ includes the Northallerton and Romanby STW in Table “A5.1: List of storm overflows spilling 20 or more times that we [Ofwat] have found in breach of Regulation 4(4) UWWTR (Urban Waste Water Treatment Regulations).”
https://www.ofwat.gov.uk/wp-content/uploads/2024/08/Notice-of-Ofwats-decision-to-accept-section-19-undertakings-from-Yorkshire-Water.pdf
Yorkshire Water’s letter of 28 July 2022 re 20/01687/OUT states:
“If planning permission is to be granted, the following conditions should be attached in order to protect the local aquatic environment and Yorkshire Water infrastructure:
No development shall take place until details of the proposed means of disposal of foul water drainage for the whole site, including details of any balancing works off-site works, the point(s) of connection and appropriate phasing of the necessary infrastructure, have been submitted to and approved by the local planning authority. If sewage pumping is required, the peak pumped foul water discharge rate must be agreed with the Local Planning Authority in consultation with the Statutory Sewerage Undertaker.
Furthermore, unless otherwise approved in writing by the local planning authority, no buildings shall be occupied or brought into use prior to completion of the approved foul drainage works. (To ensure that no foul water discharges take place until proper provision has been made for their disposal)”
“Waste Water
1) It is noted from the submitted planning application that surface water is proposed to be drained to the public surface water sewer adjacent to number 87 Winton Road approximately 27m from the site, at a maximum rate of 3.5 (three point five) litres per second. We have no objection to this proposal.
2) The public foul network within the vicinity of the site does not have adequate capacity available to accommodate the anticipated foul water discharge from the proposed development. Although the submitted Flood Risk Assessment doesn’t specify any detailed foul water proposals, we require full phasing details regarding the proposed foul water flows from all phases of the construction.”
Both Yorkshire Water and the LPA are ignoring the EDM data when assessing planning applications and the LPA is approving developments where evidence exists that there is no available capacity in the local sewerage network. In my view, it is wholly irresponsible of Yorkshire Water and the LPA to ignore the evidence. Government guidance issued in 2025 stresses the importance of using the EDM data: “It [EDM data] should be utilised by water and sewerage companies and regulators to inform daily operation, maintenance of and required upgrades to the sewerage system.”
“Storm overflows: Policy and Guidance” (Published 24 March 2025) states:
“As the legal and policy landscape has developed, so has technological capability. All storm overflows operated by water and sewerage companies whose areas are wholly or mainly in England are now fitted with event duration monitors (EDMs), allowing water and sewerage companies to report on the frequency and duration of storm overflow discharges in near real time.
EDM data provides greater insight into the operation of storm overflows than ever before. It should be utilised by water and sewerage companies and regulators to inform daily operation, maintenance of and required upgrades to the sewerage system.”
Yorkshire Water is NOT considering the EDM data when formulating its consultation responses, and North Yorkshire Council is mistakenly assuming that Yorkshire Water IS consulting the data. Neither Yorkshire Water nor North Yorkshire Council are taking into account the most important data despite clear government advice to do so.
[OFFICIAL – SENSITIVE]
In her email to me of 13 August 2025, Linda Marfitt, Head of Planning Policy & Place, North Yorkshire Council said:
“I note that national guidance now advises water and sewerage companies and regulators to use EA EDM data to inform daily operation, maintenance of, and required upgrades to the sewerage system. Therefore, this data should assist Yorkshire Water with their responses and in turn will be factored into future planning decisions.”
The data would assist both Yorkshire Water and North Yorkshire Council if both organisations were willing to fact-check the data. Why isn’t Yorkshire Water utilising the EDM data and quoting the data in its consultation responses? Why is the evidence of sewage pollution being suppressed by North Yorkshire Council?
Prior to the determination of Planning Application ZB25/01465/OUT, the LPA must secure a guaranteed timeline from Yorkshire Water that specifies when the Northallerton sewer network and STW will be investigated and treatment capacity will be increased to accommodate both the existing population of Northallerton and the additional foul waste that will be generated by a growth in population.
Coupled with the requirement to increase the capacity of the Northallerton and Romanby STW, Yorkshire Water must reduce the number of sewage spills into the local watercourse (from over 100 average spills per annum, to just 10 by 2035). The LPA should obtain both start and end dates for this upgrade work prior to the approval of the current application, to manage the expectations of applicants, developers and the public, and to ensure that the local aquatic environment and Yorkshire Water infrastructure is protected.
Application ZB25/01465/OUT should, if approved, be subject to the same condition approved by the Planning Inspectorate re Appeal Reference APP/U2750/W/25/3360685, Land north of Middleton Road, Pickering, that:
“No dwelling hereby permitted shall be occupied until confirmation has been provided to the Local Planning Authority that sufficient capacity exists within the public sewerage network and wastewater treatment works to accommodate the foul drainage flows from the development.”
I do not oppose the building of new homes but I do believe the Local Planning Authority has a duty to ensure that the necessary capacity exists in local infrastructure to support new developments, and is in place and operational, before they are built. The cart must not be put before the horse, and in terms of sewage treatment capacity Yorkshire Water must increase the capacity of its local sewerage systems before new houses are occupied.
This letter is not an objection (please mark as ‘neutral’) but it does raise serious concerns about the approach of both Yorkshire Water and the LPA in assessing this, and other, planning applications. Critical evidence (EDM data) is being overlooked by both organisations; data which shows, beyond doubt, that the Northallerton sewerage system has NO available capacity to accept any growth in population at this time.
Please upload my letter to the North Yorkshire Public Access website (NYC Planning Portal) with the following description:
“The Northallerton sewerage system has no available capacity”.
Thank you.
Simon
[OFFICIAL – SENSITIVE]