Mains water system, pressure reducing valves

Summary

The request sought total procurement, installation, and maintenance costs for pressure reducing valves installed since 2018, along with the analysis justifying their use over pipe replacement. The authority disclosed aggregate procurement costs, unit counts, and estimated installation figures, but withheld specific unit prices citing commercial sensitivity.

Key Facts

• Manx Utilities ordered 28 Pressure Management Valves (PMVs) between January 2018 and December 2025.
• 25 PMVs have been installed, with 3 currently held in stock.
• The total procurement cost for the 28 valves was £59,270.
• Specific unit costs are withheld as commercially sensitive, though the average range is estimated at £800 to £1,000.
• The estimated total installation cost for the 25 valves is approximately £130,000.

Data Disclosed

• 28
• 25
• 3
• £59,270
• £800
• £1,000
• £4,000
• £130,000
• 1st January 2018
• 31st December 2025
• three and five-year cycle

Exemptions Cited

• Commercial sensitivity regarding specific unit prices under a fixed-term agreement

Original Request

Please could you provide the total cost to date of procurement of the pressure reducing valves (PRVS) that have been installed around the islands water mains system since 2018, including the budget of expected ongoing maintenance and any other future costs considered regarding these PRVS. In particular, the cost per unit (understand if this needs to be average cost if PRVS are not identical), the number of units ordered/received/installed to date and how many PRVS are currently held in inventory by Manx Utilities. In addition an estiamte of the costs incurred to date in installing these valves. Please could you confirm what analysis was undertaken by Manx Utilities when making the decision to procure and install these PRVS in order to save water through leaks and bursts, and what considerations were were given to show these funds were best served in this way instead of using the funds to repair/replace/update the unfit water mains pipes and systems to stop leaks and bursts fully.

Data Tables (7)

Full Response Text

FOI 5179233 – Water Main Pressure

Request: Please could you provide the total cost to date of procurement of the pressure reducing valves (PRVS) that have been installed around the islands water mains system since 2018, including the budget of expected ongoing maintenance and any other future costs considered regarding these PRVS.

In particular, the cost per unit (understand if this needs to be average cost if PRVS are not identical), the number of units ordered/received/installed to date and how many PRVS are currently held in inventory by Manx Utilities. In addition an estimate of the costs incurred to date in installing these valves.

Please could you confirm what analysis was undertaken by Manx Utilities when making the decision to procure and install these PRVS in order to save water through leaks and bursts, and what considerations were given to show these funds were best served in this way instead of using the funds to repair/replace/update the unfit water mains pipes and systems to stop leaks and bursts fully. Introduction: Pressure management is a fundamental component of efficient water network operation, helping to reduce leakage, control burst frequency, and extend the lifespan of infrastructure. By regulating excessive pressure—particularly in areas with variable elevation or ageing assets—utilities can significantly lower daily water losses and improve overall system performance. This approach also supports environmental goals by reducing the volume of treated water lost through leaks, which in turn lowers energy use and operational costs. On the Isle of Man, pressure management is not just beneficial but essential due to the island’s steep and varied topography. High elevation differences across relatively short distances can result in extremely high pressures in low-lying areas, placing considerable stress on pipes and fittings. To mitigate this, pressure management valves (PMV’s) and control systems are widely deployed to stabilise supply, protect infrastructure, and maintain consistent service levels. Similarly, UK utilities have adopted smart pressure control technologies to optimise performance, meet regulatory leakage targets, and enhance long- term network resilience. For clarity, Manx Utilities currently refer to the valves in question as Pressure Management Valves (PMV’s/PMV) which are the same as Pressure Reducing Valves (PRV’s/PRV). Some older documentation may refer to PRV’s/PRV, please assume that this has the same meaning as PMV’s/PMV. PMV Costs since 2018: Procurement Costs for PMV’s: From 1st January 2018 until 31st December 2025 Manx Utilities ordered 28 PMV’s. The cost for procurement of those PMV’s is £59,270. Current PMV Unit costs: The specific prices for pressure management valves (PMV’s) are subject to a fixed-term agreement and are therefore commercially sensitive. As such, we are unable to disclose exact unit costs. However, to assist with your request, we can advise that the average cost for the most commonly used PMV sizes on our network typically falls within the range of £800 to £1,000 per unit. Number of PMV’s Info: Number of PMV’s Ordered 28 Number of PMV’s Installed 25 Number of PMV’s in Stock 3

Estimated Installation Costs: Installation costs can vary significantly due to the design of the particular layout and also unpredictable nature of ground conditions encountered during excavation and the potential for unforeseen complications on site. We do not keep specific costings for installation as the price varies per job. The following is an estimation and not fixed information: the cost of installing a chamber with a pressure management valve (PMV) is estimated to be in the region of approximately £4,000, subject to the factors outlined above. The total estimated installation cost for all 25 installed PMV’s combined is approximately £130,000, again there is no set figure this an estimation and this figure is subject to variation depending on site-specific conditions. Costs could be higher if complications arise during the works, but may also be lower if the main is shallower than anticipated or if ground conditions and backfill materials are easier to excavate and reinstate. Maintenance Costs: Each PMV undergoes routine servicing on a three and five-year cycle, carried out in-house by the maintenance team. For newly installed units, it is uncommon for any components to require replacement during the initial service. Maintenance kits, which vary in cost from approximately £80 to £200 depending on valve size, are typically used to replace consumable items such as rubber components and washers. The main body and internal components, predominantly constructed from durable ductile iron, generally exhibit minimal wear and do not usually require replacement. Estimated ongoing maintenance costs are approximately £200–£300 per service (every three years) if component replacement is required. This figure excludes labour, as man-hour costs vary depending on the specific components needing replacement for each PMV. The maintenance team operates under a general maintenance budget that covers all network assets, including valves, hydrants, PMV’s, and air valves. As such, there is no dedicated budget specifically allocated for PMV maintenance. Pressure Management Analysis: Manx Utilities commissioned an external consultant/specialist in 2015 to assess potential pressure management schemes and their associated benefits. The resulting report identified areas of the network where pressure control would deliver the greatest impact in terms of reducing water usage, minimising leakage, and alleviating stress on ageing infrastructure. It also provided estimated savings across key metrics, including water volume, burst frequency, and overall cost efficiency. The report provided a strategic framework for the placement of pressure management valves across the network, which has since guided the implementation of recent schemes. In several cases, actual reductions in daily water volume have significantly exceeded the report’s projections, with some installations achieving savings up to twice those originally estimated.
Savings Case Studies: Pressure management is recognised as a sustainable and cost-effective strategy for reducing both water consumption and the long-term costs of maintaining the water network. The following examples highlight recent installation schemes that have delivered significant savings across the network. The three below schemes combined save an estimated 600 m³ (600,000 litres) per day, which is an annual saving of over 200 million litres or 80 Olympic- sized swimming pools. Sydney Street PMV: The PMV was installed in 2023 below are the savings that have been seen so far since the installation: Water Volume Savings: The pressure management valve (PMV) installed at Sydney Street is currently achieving an estimated daily water saving of approximately 100 m³ (100,000 litres), representing a reduction of around 17% in daily water volume. This equates to an annual saving of roughly 35 million litres.
Repair Jobs Completed Annually: Date Range Repair Jobs Completed 2017-2019 (Pre-PMV) 43 2023-2025 (Post-PMV) 5 The years 2020-2022 have not been selected due to the impact COVID had on general repairs being completed. Since the PMV has been installed and fully optimised there has been an 87% reduction in repair jobs in the area. Port Erin Wastewater Meter (WWM) PMV: The PMV was installed in 2022, below are the savings that have been seen so far since the installation: Water Volume Savings: The pressure management valve (PMV) installed at Port Erin WWM is currently delivering estimated daily water savings of approximately 350 m³ (350,000 litres), representing a 37% reduction in daily water volume. This equates to an annual saving of around 127 million litres.
Repair Jobs Completed Annually: Date Range Repair Jobs Completed 2017-2019 (Pre-PMV) 68 2023-2025 (Post-PMV) 8 The years 2020-2022 have not been selected due to the impact COVID had on general repairs being completed. Since the PMV has been installed and fully optimised there has been an 88% reduction in repair jobs in the area. Vicarage Road PMV: The PMV was installed late in 2024, below are the savings that have been seen so far since the installation: Water Volume Savings: The PMV installed at Vicarage Road is currently achieving estimated daily water savings of approximately 150 m³ (150,000 litres), representing a 14% reduction in daily water volume. This equates to an annual saving of around 54 million litres. Repair Jobs Completed Annually: Date Range Repair Jobs Completed 2017-2019 (Pre-PMV) 26 2024-2025 (Post PMV) 7 The years 2020-2022 have not been selected due to the impact COVID had on general repairs being completed. Since the PMV has been installed and fully optimised there has been a 73% reduction in repair jobs in the area. PMV Burst Reduction Savings Estimate Table: PMV Name Water Saved Annually (Litres) Repair Reduction (No. of jobs per year) Cost of repair reduction per year (estimate) (£) Sydney Street PMV 35 million 13 £45,500 Port Erin WWM PMV 127 million 20 £70,000 Vicarage Road PMV 54 million 7 £24,500 The table above outlines the estimated cost savings achieved through burst reductions as a result of pressure management. It highlights the decrease in repair jobs since implementation and provides an estimate of the associated financial savings. Comparing Results to Analysis Report: The three schemes referenced above were originally estimated to deliver combined daily water savings of 286 m³, according to a 2015 analysis report. However, real-world performance has shown actual savings of approximately 600 m³ per day—more than double the predicted volume.
When combined with the observed reduction in burst frequency across managed areas, the demonstrated impact of pressure management is substantial—delivering significant benefits to both the water network and its users. In addition to reducing leakage, lower operating pressures help preserve ageing mains by minimising stress on vulnerable pipework, thereby extending asset life and reducing the need for reactive maintenance or premature replacement. Based on the outcomes of these three projects, it is reasonable to suggest that many of the proposed pressure management schemes could achieve real-life water savings up to twice those originally estimated in the analysis report. Comparative Rehab Replacement: The following provides a preliminary cost estimate for replacing all water mains across each of the areas listed above.
Water Network Area Length of water mains (m) Area of water main trench (m2) Approximate Price of mains replacement (£130 per m) in £ Price of tarmac (£260 per m2 for footpath) (£280 per m2 for road) Total Cost of mains install and tarmac (£) Port Erin WWM 26,000m 23,400m2 £3.40 million £6.30 million £9.7 million Sydney Street 9,750m 8,775m2 £1.25 million £2.37 million £3.62 million Vicarage Road 41,052m 36,946m2 £4.80 million £8.62 million £13.42 million

These cost estimates are based on the typical surface area required to reinstate a standard water main trench. However, in many locations across the island, MUA is required (by law) to carry out full carriageway reinstatement rather than a simple patch repair—significantly increasing the actual cost. The quoted mains replacement figure covers excavation and installation of the new main only and does not include any tarmac reinstatement, this is also an estimation as we are unable to get the available figure. Without a full network replacement, it would be impossible to eliminate all leaks and bursts. In high-pressure areas, repairing one section of main often results in the next weakest point failing shifting the problem rather than resolving it. Analysis Summary: It is widely accepted in the water industry that the introduction of pressure management, including the use of PMV’s is a highly cost-effective and efficient strategy for reducing water consumption and leakage while significantly extending the life of ageing water infrastructure.
By proactively managing excessive pressure, utilities can minimise burst frequency and network stress, deferring the need for widespread mains replacement. As demonstrated above, this targeted approach delivers substantial operational and financial benefits at a fraction of the cost of full-scale rehabilitation.

PROPOSED PRESSURE MANAGEMENT SCHEMES SUMMARY only phase can be edited without password Scheme Name REPORT Investment / Offsite Works Required NEW PRV CONTROL LER OTHER BENEFITS Closest Valve Asset ID DMA(s) X Y PMA Mains Length (km) EXISTING D/S CONTROL PRESSURE AZNP HTD AVERAGE BURST FREQUENCY BURST FREQUENCY (Burst/100km/Yr) PROPOSED D/S CONTROL PRESSURE AZNP After HTD % Reduction Burst Frequency BURST FREQUENCY (Burst/100km/Yr) Est. BURST REDUCTION / yr Est. Reduction m3/day WATER SAVING £ BURST SAVING £ TOTAL SAVING £ SCHEME COST £ COST BENEFIT VIABLE? Suggested Schemes for Implementation Sum1 CLANNAUGH RD PMV COMPLETE NEW PMV & FLOW MODULATED CONTROLLER YES YES - 1030010079 DMA 424 - CLANNAUGH ROAD SULBY 238006 494407 19.95 n/a 87.3 23.1 8.8 43.9 FLOW MOD 29.9 24.2 80% 8.710 7.027 156 28,470.00 £
35,136.84 £
63,606.84 £

N/A

N/A

PHASE 1 PHASE 1_NEW PMV & FLOW MODULATED CONTROLLER PORT ERIN WASTE PMV COMPLETE NEW PMV – FIXED OUTLET CONTROL YES - - 1010078495 DMA 445 - PORT ERIN Waste 220569 468861 14.64 n/a 87.6 21.9 8.8 60.3 45 45.5 23.8 76% 14.658 6.677 142 25,909.91 £
33,386.03 £
59,295.94 £

N/A

N/A

PHASE 1 PHASE 1_NEW PMV – FIXED OUTLET CONTROL CASTLETOWN PMV (FIXED) COMPLETE OPTIMISATION OF EXISTING PMV - - - 1050000070 DMA 423 - CASTLETOWN 225562 468351 18.76 52 53.4 23.1 5.9 31.7 28.5 29.5 23.5 64% 11.367 3.809 135 24,705.37 £
19,043.25 £
43,748.62 £

N/A

N/A

PHASE 1 PHASE 1_OPTIMISATION OF EXISTING PMV PORT ERIN PMV COMPLETE NEW PMV & FLOW MODULATED CONTROLLER YES YES - 1030007036 DMA 471 - PORT ERIN 223107 470066 14.75 n/a 83.7 22.6 3.2 21.9 FLOW MOD 60.2 25.1 42% 12.715 1.359 103 18,765.55 £
6,796.76 £
25,562.30 £

N/A

N/A

PHASE 2 PHASE 2_NEW PMV & FLOW MODULATED CONTROLLER SYDNEY STREET PMV COMPLETE NEW PMV – FIXED OUTLET CONTROL YES - - 1030003556 DMA 458 - SYDNEY STREET 237837 476173 5.53 n/a 74.5 22.8 2.9 52.0 21 29.7 23.8 81% 10.073 2.318 90 16,410.10 £
11,588.32 £
27,998.42 £

N/A

N/A

PHASE 1 PHASE 1_NEW PMV – FIXED OUTLET CONTROL BALLACALLIN PMV COMPLETE NEW PMV & FLOW MODULATED CONTROLLER YES YES - 1010113795 DMA 410 - BALLACALLIN 224223 481736 33.23 n/a 58.0 22.2 12.4 37.2 FLOW MOD 43.3 24.3 47% 19.722 5.799 81 14,867.44 £
28,995.

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