Is my site subject to the 110 litres optional requirement?

Why there is no list of councils here

The obvious thing to publish would be a register of which authorities require 110 l/p/d. We looked into it and decided against, for a reason worth stating plainly: a list of councils would answer the wrong question. Because the optional requirement is engaged by the condition on your permission, a correct list of Local Plan policies still would not tell you what applies to your scheme — policies have exceptions, phasing and viability negotiations, and permissions granted before a policy was adopted will not carry the condition. Someone who found their council on such a list and built to 110 without a condition, or missed it and built to 125 with one, would be worse off than with no page at all.

There is also no authoritative list to build from. Neither gov.uk, the Planning Practice Guidance, the Environment Agency, Defra nor the Planning Portal publishes one. The only aggregate figure in circulation is a count of 80 authorities, which Defra's own 2025 consultation attributes to the Environment Agency as of 2017 and does not name.

How the requirement is actually triggered

Regulation 36 of the Building Regulations 2010 puts it in two steps. The requirement is either 125 l/p/d, or the optional requirement of 110 l/p/d "in a case to which paragraph (3) applies". Paragraph (3) applies where the planning permission under which the work is carried out:

1. "specifies the optional requirement in paragraph (2)(b)"; and
2. "makes it a condition that that requirement must be complied with".

Both limbs, on the permission. That is the whole test. Everything else — the Local Plan, the water stress designation, the water company's own asks — is the reasoning that leads an authority to impose the condition, not a substitute for it.

Checking your own site, in five minutes

1. Find the decision notice for the permission the work is being carried out under — not the application, the decision.
2. Search it for litres, 110, water efficiency, Part G and optional requirement.
3. A condition naming the optional requirement means your calculation has to demonstrate 110 l/p/d. In London, a condition citing London Plan Policy SI 5 and 105 l/p/d excluding external use is the same target — the Part G calculation adds a fixed 5 l/p/d of external use at the end, so 105 excluding and 110 including are the same number.
4. No such condition means the requirement is 125 l/p/d.
5. Ambiguous? The planning case officer and your building control body can both confirm it. Get it in writing before the sanitaryware is ordered.

Your Local Plan is still worth reading — it tells you what to expect on the next application. It just does not change the one you already have.

The Environment Agency's water stressed areas classification

This is the evidence an authority most often relies on when it sets a 110 l/p/d policy. The Secretary of State's current determination dates from 1 July 2021 and has not been updated since. It classifies water company supply areas, not councils — 15 of the 23 areas are in serious water stress.

Read what the Environment Agency says about using it. The determination states that local authorities "can use the water stress determination to inform whether they can require the tighter standard of 110 litres per head per day in new developments", and that otherwise its use "is only to allow water companies to consider compulsory metering in their water resources management plans. It must not be used for other purposes such as development planning or water resources planning." Being in a stressed area is not a requirement landing on your site.

Source: Water stressed areas — 2021 classification, Environment Agency and Defra, published 1 July 2021. Read from the published report on 2026-09-19; the numbering and the company names are the Environment Agency's own, including "Veolia Water", which is the entity name the determination carries. The determination itself is reserved by the Environment Agency, so the classification is reported here as fact with attribution — the report's text, method and map are not reproduced. Note the sub-company splits: Severn Trent is designated excluding its Chester zone, and Anglian's Hartlepool area and South West Water's Devon and Cornwall area are not designated while their other areas are.

Where the policy stands, as at 2026-09-19

• Regulation 36 — unchanged. 125 l/p/d, or 110 where a planning condition specifies the optional requirement.
• Approved Document G — unchanged since the 2024 amendments were incorporated on 1 October 2024.
• Defra's review — no response yet. The consultation on cutting the baseline to 105 l/p/d and the optional requirement to 100 closed on 16 December 2025, proposing amendment during 2026 followed by a six-month transition. No government response has been published.
• NPPF, August 2026 — new wording. Policy PM13 allows plan policies on water efficiency to apply "the tighter Building Regulations optional requirement where justified, or exceptionally a more stringent local standard in areas of serious water stress", and policy CC1 asks plans to set local water efficiency standards where PM13 justifies them.

That last one leaves a gap nobody has closed: regulation 36 offers 125 or 110 and nothing below, so a "more stringent local standard" has no Building Regulations hook and would have to be secured and evidenced through planning on its own terms.

Once you know your target

WaterMonkey runs the Part G calculation against 125, 110 or a custom target with live PASS/FAIL as you change the fittings — free in your browser, with the Building Control PDF at £25 +VAT. The 110 l/p/d planning condition guide covers what hitting the tighter number actually takes, and the London page covers Policy SI 5.

Frequently asked questions