Running an HMO in London means juggling a lot of paperwork. Gas safety, electrical reports, fire alarms, fire doors, and a licence application that seems to get longer every time. Hot water safety doesn't always make the top of the list. It should at least make the list, and if you've got thermostatic mixing valves in the house, they need looking after like everything else.
A quick refresher on HMO licensing in London
Under the Housing Act 2004, larger HMOs (five or more people forming more than one household) need a mandatory licence from the council. On top of that, many London boroughs run additional licensing schemes that bring smaller HMOs into licensing, and some run selective licensing for other private rented homes too. Schemes start, end and get renewed, so it's worth checking your own council's website rather than relying on what a friend with a flat in the next borough told you.
Every licence comes with conditions. Some are standard, and some are set locally. That's the bit to read properly, because licence conditions and amenity standards vary from borough to borough. One council may say a lot about bathrooms and hot water, another very little.
Where hot water and scalding come in
Whatever your licence says, councils assess housing conditions using the Housing Health and Safety Rating System (HHSRS). Burns and scalds, including from hot water, are one of the hazards it covers. An environmental health officer looking round an HMO may well run a hot tap and ask how the temperature is controlled, particularly if any of your tenants are older, disabled or have young children visiting.
There's also the Legionella side. Landlords have a duty under health and safety law to assess and control the risk from Legionella in the water systems they provide, following the approach in ACOP L8 and HSG274. That means hot water needs to be hot enough to control bacteria, which in turn means it can be hot enough to scald. TMVs are the usual way to square that circle at the outlet.
Worth knowing: there's no blanket rule that every London HMO must have a TMV on every outlet. It depends on the property, the hot water system and who lives there. But if TMVs are fitted, they need to work, and you need to be able to show they've been checked.
Where you'll find TMVs in an HMO
- Under baths. In conversions done in the last couple of decades, Building Regulations Part G usually means bath hot water in new flats is limited to 48°C, and a TMV is the common way to do it.
- On en-suite showers. Many thermostatic shower mixers do the TMV job in the same body as the controls, so they count too.
- On basins, especially in shared bathrooms or where a tenant has particular needs.
- Hidden somewhere odd. Behind a tiled-in panel, in an airing cupboard, or above a ceiling in a property that's been refurbished three times by three different firms.
Why HMO valves need more love than most
Shared bathrooms get hammered. Five or six people showering every morning puts far more hours on a valve than a single family would. Add London's hard water and you get scaled strainers and sluggish cartridges quicker than you'd expect. If you're curious about what scale actually does inside a valve, we've written about hard London water and TMV limescale.
Then there's turnover. Tenants come and go, nobody stays long enough to notice the shower creeping hotter over a year, and complaints often arrive via a letting agent as "the shower's playing up". By the time it reaches you, a quick service might have become a cartridge replacement.
What helps at licensing and renewal time
We can't tell you what your council will ask for, because it varies. What we can say is that tidy records rarely hurt. For TMVs, that means:
- A list of every valve in the property, with where it is and what it serves. Our asset registers do exactly this.
- A recent service certificate for each one, showing temperatures and a passed fail-safe test.
- A sensible interval. For a busy shared house in hard water, six-monthly or annual servicing is typical. Your Legionella risk assessment should back it up.
- A plan for anything that failed, with dates.
Keep it with your Legionella risk assessment and your other certificates, so it's all in one place when the council or your managing agent asks.
A typical scenario
Imagine a landlord in Ealing with a six-bedroom HMO coming up for licence renewal. The house has two shared bathrooms, three en-suites and a TMV under each bath, fitted when it was converted. Nobody has touched them since. On a visit like that, we'd service each valve, record the readings, label them so the next visit is quicker and flag the one that won't shut off properly on the fail-safe test. The landlord ends up with certificates, a short register and a quote for one replacement cartridge, all of which sits neatly alongside the rest of the renewal paperwork.
Portfolios across London
Lots of HMO landlords have a few houses rather than one, and they're rarely in the same street. We group visits by area so a portfolio spread across West London and East London can be done in a sensible order, and every property ends up on the same schedule. We'll also arrange access with your tenants or agent, and come back for any rooms we couldn't get into.
The short version
Read your own borough's licence conditions, because they differ. If you have TMVs, keep them serviced and keep the certificates. And if you're not sure what's behind the bath panels, find out before the council does.
See our TMV servicing page for what a visit involves, or the TMV compliance guide for the background on temperatures and guidance.
Got TMVs in London that need a look?
Tell us roughly what you've got and where. We'll give you a fixed quote and a date that works around your building.