HMOs must meet specific bathroom and toilet ratios to obtain and maintain an HMO licence in London. This guide covers the HHSRS standards, London borough requirements, room sizing minimums, and what improvements are most commonly required.
Minimum Bathroom and Toilet Standards for London HMOs
The Management of Houses in Multiple Occupation (England) Regulations 2006 and the Housing Health and Safety Rating System (HHSRS) set out minimum standards. London boroughs apply these through their HMO licensing conditions, often adding local requirements on top of the national minimum.
Occupant-to-Bathroom Ratios
The nationally accepted minimum standard (and the standard applied in most London borough HMO licence conditions) is:
- 1 bathroom for up to 4 persons
- 2 bathrooms for 5-9 persons
- 3 bathrooms for 10-14 persons
Note: Many London boroughs apply stricter ratios. Hackney, Tower Hamlets, Newham, and Haringey require one bathroom per 5 persons rather than per 4. Always check the specific licensing conditions for your borough.
What Counts as a Bathroom?
For HMO licensing purposes, a bathroom must contain at minimum: a bath or shower, a wash hand basin, and a WC. A shower room without a WC and a separate toilet do not combine to count as one bathroom — each bathroom facility must contain all three elements unless separate toilet provision is explicitly acceptable under the licence conditions.
The trend in London is toward en-suite rooms — adding en-suites increases lettable value significantly (£50-200/month premium per room) while also improving the bathroom ratio.
Minimum Room Sizes
Minimum bathroom sizes for HMOs in London are not nationally standardised but typical licence conditions require:
- Full bathroom (bath, basin, WC): minimum 3.2m² floor area
- Shower room (shower cubicle, basin, WC): minimum 2.5m²
- Separate WC with basin: minimum 1.1m²
Hot Water Requirements
Under HHSRS and standard HMO licence conditions:
- Hot water must be available at all reasonable times (cannot be time-restricted without cause)
- Water temperature at point of use must be capable of reaching 50°C within one minute
- Thermostatic mixing valves (TMVs) must be fitted to prevent scalding where vulnerable occupants may be present
- Hot water storage must provide minimum 35 litres per person in HMOs with cylinders
Ventilation
All HMO bathrooms must have mechanical ventilation (extractor fan) unless a window is present that provides adequate purge ventilation. The fan must be intermittent (running during and after use) with a minimum air change rate of 15 litres/second for bathrooms and 6 litres/second for separate toilets.
Frequently asked questions
Can I convert a bedroom to a bathroom to improve the HMO ratio?
Yes — and this is one of the most common HMO improvements in London. Converting a bedroom to an en-suite or shared bathroom increases the bathroom ratio, allows the council to license more occupants, and increases per-room rental income. Planning permission is generally not required for internal bathroom additions in residential properties.
Does every HMO bedroom need an en-suite?
No — shared bathrooms are acceptable in most London HMO licence conditions provided the ratio (typically 1 bathroom per 4-5 occupants) is met. However, en-suite rooms command a £50-200/month premium in London and are increasingly the market expectation for professional sharers in zones 2-4.
What is the hot water requirement for an HMO with 7 bedrooms in London?
For a 7-person HMO, your hot water system must provide hot water available at all reasonable times, reaching 50°C within one minute at the tap. Using a cylinder system, minimum 245 litres storage capacity (35 litres × 7 persons) is typically required. Peak demand in a 7-person HMO (6:30-8:30am) is significant — undersized cylinders are a common licensing failure point.
My HMO bathroom has a window but no extractor fan — is this acceptable?
Possibly — if the window is openable and provides adequate purge ventilation (minimum 1/20th of floor area, openable to provide at least 1/20 equivalent area). However, most London HMO licence conditions and Part F Building Regulations require mechanical ventilation (extractor) in all bathrooms regardless of window provision, because windows are rarely opened in cold weather. Fit an extractor as standard.