One datacentre asked for as much water as 3, 500 homes, and planners didn’t model that demand
A proposal to draw up to 3 million litres of potable water a day for a single datacentre (Affinity Water submission to MPs) has pushed a simple question into boardrooms and planning teams: who assumed the country always has enough water to support a boom in digital infrastructure?
Water UK told MPs that several national AI and datacentre policy documents were not included in the demand models used by water planners, leaving project‑level allocations unmodelled (Water UK briefing to MPs). That sits alongside another fact: the Environment Agency’s National Framework for Water Resources (published 17 June 2025) explicitly calls out “emerging technologies, such as datacentres” as a future pressure on supplies, but does not seem to include detailed, project‑level demand estimates for the sector (Environment Agency, National Framework, 17 June 2025). In short: the EA recognises the risk in principle, while industry bodies say forecasting and modelling have not yet captured the scale and clustering of actual proposals.
What the headline numbers show (and who reported them)
- 3 million litres/day for one site: reported by Affinity Water as an allocation some datacentre projects requested in its region (Affinity Water submission to MPs). Affinity compared that request to the peak consumption of about 3, 500 homes, which implies roughly 860 litres per home per day based on the numbers cited (3, 000, 000 ÷ 3, 500 = ~857 L/home/day) (Affinity Water submission to MPs).
- 5 billion litres/day national shortfall by 2055: projected in the Environment Agency’s National Framework for Water Resources (Environment Agency, National Framework, 17 June 2025).
- Current and potential datacentre potable use: Water UK estimates datacentres in England currently use about 6.6 million litres of drinking water per day and that figure could reach about 19.8 million litres/day if datacentre capacity triples by 2030 (Water UK briefing to MPs).
- Geographic clustering: Water UK and regional operators say more than three‑quarters of UK datacentres are concentrated in the south and east of England (Water UK statement to MPs). Affinity Water reported roughly 125 datacentre projects proposed or under construction in its Slough area region (Affinity Water submission to MPs).
- Leakage and reductions: Water UK states water companies have cut leakage by around 40% since privatisation and plan a further 17% reduction by 2030 (Water UK statement).
- Public campaigns: water companies, Ofwat, the Environment Agency, the Met Office and Natural Resources Wales announced a joint campaign to encourage lower household water use (announced end of June) (industry announcement, end of June).
Why this is more than a policy blind spot
Three realities make the gap meaningful for executives:
- Datacentres can use a lot of potable water. Evaporative cooling (cooling towers), chillers and humidification systems draw direct water for heat dissipation, and high electricity demand creates indirect water pressure through power‑station cooling and generation footprints. Under current Environment Agency permitting practice many operations have relied on potable (drinking‑quality) supplies (Environment Agency guidance; Water UK briefing to MPs).
- Supply solutions take time. Major infrastructure, reservoirs, desalination and large recycling projects, needs long lead times and complex permitting. The National Framework flags reservoirs, desalination and recycling among the measures needed to close the projected gap (Environment Agency, National Framework, 17 June 2025).
- Industry clustering concentrates local risk. When most new capacity is located in water‑stressed regions, local allocation constraints become a hard cap on expansion and a source of planning and commercial friction (Water UK statement; Affinity Water submission to MPs).
Politics and prioritisation, who gets water in a drought?
Water UK has asked ministers to publish a drought hierarchy, a clear sectoral order for allocations during shortages, warning that without it there will be “trade‑offs across society” (Water UK briefing to MPs).
Jon Chappel, deputy director at Water UK, called the omission “unforgivable” and a “genuine failing of government.” (Jon Chappel, Water UK briefing to MPs)
The picture is more complex because some datacentres may be designated critical national infrastructure (CNI). CNI status affects emergency planning and protection, but it does not automatically guarantee water allocations, formal prioritisation depends on the drought hierarchy and the operational guidance ministers put in place. Oliver Hayes of Global Action Plan warned of a perverse outcome: “I think it is highly likely that we’re going to end up seeing datacentres that are actually running chatbots, or enabling people to do benign and very wasteful, pointless things, protected and given favourable treatment when it comes to resources.” (Oliver Hayes, Global Action Plan)
Leaks and demand management: part of the toolkit, not the whole solution
The Environment Agency’s framework expects a mix of demand management, leakage reduction and new supply to close deficits (Environment Agency, National Framework, 17 June 2025). Industry statements back that up: Water UK points to substantial historical leakage reductions and further targets (Water UK statement). Campaigns to reduce household use were also announced by water companies and regulators at the end of June (industry announcement, end of June).
Critics note distribution leakage remains a stubborn problem and that demand campaigns alone will not resolve clustered industrial demand. Greenpeace has criticised ongoing leakage from pipes as a major waste (Greenpeace comment), while industry bodies emphasise that solving the gap requires both behavioural change and large capital projects.
Where the planning gap translates into business risk
For datacentre owners, cloud buyers and infrastructure investors, the modelling omission creates three material risks:
- Permitting and siting risk: local regulators may decline or condition new abstractions in water‑stressed areas, delaying projects or increasing capital costs (Affinity Water submission to MPs; Water UK briefing to MPs).
- Operational risk in droughts: without a clear drought hierarchy, operators could face temporary restrictions on potable supplies or be forced to relocate workloads at short notice (Water UK briefing to MPs).
- Reputational and regulatory risk: visible high potable water use during shortages can trigger public backlash and tougher local constraints for the industry (Affinity Water submission; civil society commentary).
High‑impact levers that reduce potable‑water exposure (and procurement risk)
Not all levers are equal. The highest‑impact, most actionable approaches for reducing reliance on potable mains are listed first, with a short note on trade‑offs.
- Use non‑potable supplies where feasible, recycled water, treated wastewater or industrial non‑potable networks cut potable demand sharply. Trade‑offs: requires new pipework, treatment agreements and regulatory approvals; time and capex needed but maximum water saving potential (Environment Agency guidance; Water UK briefing to MPs).
- Specify low‑water cooling architectures, closed‑loop chillers and air‑cooled systems reduce evaporative losses; liquid immersion cooling can dramatically cut water use but changes procurement and maintenance regimes. Trade‑offs: capital and design changes; some solutions need longer procurement cycles and operator retraining.
- On‑site recycling and heat reuse, capture and reuse process water and deploy waste‑heat recovery to create local value and reduce overall thermal loads. Trade‑offs: site‑specific engineering and partnerships with local heat users may be required.
- Contractual drought protections, SLAs and RFPs that include drought clauses, workload relocation plans and clearly defined service degradation paths limit commercial surprise. Trade‑offs: contracts become more complex and may shift liability to customers.
- Partner on local resilience projects, co‑funding or facilitating non‑potable networks, local recycling plants or accelerated supply infrastructure aligns operators with community resilience. Trade‑offs: requires longer‑term community engagement and upfront investment, but reduces future allocation risk (Environment Agency, National Framework, 17 June 2025).
Key questions every CEO, CFO and infrastructure lead should be able to answer
- Are national water forecasts accounting for datacentre growth?
Water UK has told MPs that several AI/datacentre policy documents and project proposals were not modelled into demand forecasts (Water UK briefing to MPs). The Environment Agency’s National Framework (17 June 2025) recognises datacentres as an emerging demand driver but does not appear to include detailed project‑level demand estimates (Environment Agency, National Framework, 17 June 2025).
- How much potable water do datacentres in England use today, and how might that change?
Water UK estimates current potable use by datacentres at about 6.6 million litres/day and warns that could reach about 19.8 million litres/day if capacity triples by 2030 (Water UK briefing to MPs). These figures reflect Water UK’s modelling assumptions; ask Water UK for the methodology behind the numbers when evaluating local impact.
- Could datacentres be prioritised over households in a drought?
CNI designation can influence emergency planning, but priority for water supplies depends on a formal drought hierarchy and operational decisions by ministers and regulators. Water UK has pressed for publication of a drought hierarchy because, it says, the absence of clear rules risks trade‑offs across society (Water UK briefing to MPs).
- Are there quick technical fixes to lower potable consumption?
Yes. Moving to non‑potable supplies, specifying low‑water cooling designs, adding on‑site recycling and embedding drought clauses in contracts can reduce potable demand materially. Some fixes are implementable at procurement or design stages; others need capital projects and regulatory approvals (Environment Agency guidance; Water UK briefing to MPs).
Three pragmatic steps to take this quarter (90‑day checklist)
- Map exposure: overlay your top‑priority sites with the Environment Agency’s regional deficit maps and flag any located in EA‑identified deficit or high‑pressure areas (Environment Agency, National Framework, 17 June 2025). Request written water‑usage figures from current suppliers and prospective datacentre partners.
- Lock procurement standards: amend RFPs and SLAs to require disclosure of potable‑water use and to prioritise low‑water cooling or non‑potable supply readiness as a pass/fail criterion.
- Engage locally: open formal dialogue with local water companies and regulators. Request a written assessment of the likelihood of abstraction allocations and any conditionality attached to large requests (Affinity Water submission to MPs; Water UK briefing to MPs).
Longer‑term playbook for infrastructure and policy
- Fund feasibility studies for non‑potable supply or joint resilience projects in high‑pressure regions.
- Work with industry groups to press for a published drought hierarchy and transparent, project‑level demand modelling in national water plans (Water UK request to ministers).
- Include water‑risk in site selection and financial modelling as a material operational risk, not an assumption that mains supply will always be available.
Final note
The rapid expansion of datacentre capacity is an industrial and digital ambition with real water consequences. The Environment Agency’s National Framework sets out a difficult horizon (Environment Agency, National Framework, 17 June 2025), and Water UK and regional suppliers are sounding the alarm that modelling and policy have not yet caught up with clustered, high‑intensity proposals (Water UK briefing to MPs; Affinity Water submission to MPs). For businesses, the immediate question is not whether the UK will build more capacity, it is how to build and buy that capacity without turning potable mains water into an unpriced constraint on operations and reputation. Treat water like the strategic input it is: locate risk, harden contracts, and fund local solutions before scarcity becomes a surprise.