Our use of cookies Water meters: How they work, types and how to read them
If you’re trying to get a handle on your water usage, understanding your water meter is the best place to start. Accurate meter readings mean accurate bills, earlier leak detection and a clearer picture of where your water is going.
Meters are also central to how Britain manages its water resources, particularly in high water-stress areas of the southeast, where suppliers are rolling out meters to improve efficiency across the network.
In this guide, our water experts cover everything you need to know:
- What is a water meter?
- How does a water meter work?
- Types of water meters
- Where water meters are located
What is a water meter?
A water meter is a device that measures the volume of water flowing from the mains network into a property. It gives an accurate record of exactly how much water has been used, which is then used to calculate your bill.
Most commercial properties in the UK are metered by default, with water charges calculated based on actual consumption.
Domestic properties are more mixed: newer homes tend to be built with meters as standard, while older homes may still be on unmetered bills based on the property’s rateable value. The exception is where a homeowner requests a meter or lives in a water-stressed area where metering is compulsory.
Whether the property is a business or a home, every water meter does the same core job: measuring every cubic metre of water that passes through, so that you only pay for what you actually use.
How does a water meter work?
A water meter works by measuring the volume of water that flows from the mains supply into your property. The process is simple and happens automatically whenever water is drawn through the pipe, whether that’s someone filling a kettle, flushing a toilet or running a dishwasher.
Every water meter follows the same three-stage process:
1. Water flows in
Water enters the meter from the mains supply pipe as soon as a tap, appliance, or system draws it into the property.
2. The internal mechanism measures the volume
Inside the meter, a small mechanism responds to the flow of water. In mechanical meters, this is usually a rotating impeller or piston that turns as water passes through. In newer electronic meters, sensors detect the flow using ultrasonic or electromagnetic signals.
3. The reading is recorded
Each rotation or signal is converted into a unit of volume, measured in cubic metres. The total is displayed on the meter dial and builds up over time, giving a running record of everything that has passed through since installation.
When your supplier takes a reading, either manually or remotely through a smart meter, they compare the latest figure against the previous one. The difference is the volume used during that period, and that’s what you’re billed for.
How water usage is measured and recorded
Water usage is measured in cubic metres (m³), the standard unit used across the UK water industry. One cubic metre is equal to 1,000 litres, roughly the amount of water a typical household uses in five to seven days, or enough to fill around 12 standard baths.
Every time water is drawn into the property, the meter adds the volume to a running total. That total keeps building over the lifetime of the meter, so the figure on the dial today reflects every cubic metre that has ever passed through it, not just your current billing period.
To work out how much water you’ve used over a given period, your supplier takes two readings: one at the start and one at the end. The difference between the two figures is your actual consumption, and that’s the number your bill is based on.
For example, if your meter read 00427 m³ at the start of the quarter and 00463 m³ at the end, you’ve used 36 m³ of water over that period. Your supplier then multiplies that figure by their unit rate under your business water rates tariff, adds any standing charges, and issues the bill.
For business properties, readings can be taken in a few different ways:
- Manual reads taken by a meter reader who visits the site.
- Customer-submitted reads where you note the figure and send it to your supplier.
- Automatic meter reads (AMR), where a smart meter transmits the data remotely.
Accurate, regular reads are important because they prevent estimated bills, which can lead to over or undercharging. If you’re on a metered supply and haven’t had a read taken for a while, it’s worth submitting one yourself or asking your supplier to arrange a visit.
Types of water meters
Water meters fall into three main categories: mechanical, digital and smart. Each works slightly differently, but all serve the same purpose of measuring how much water passes from the mains into a property.
The type installed at your property will depend on when it was fitted, your water supplier and whether your property is in an area where smart meters are being rolled out.
Mechanical water meters
Mechanical meters are the traditional type and still the most common across UK properties.
Inside the meter sits a small spinning mechanism, usually an impeller or piston, which turns as water passes through it. Each rotation corresponds to a fixed volume of water, and those rotations drive a set of numbered dials on the front of the meter that display the total volume used in cubic metres.
Mechanical meters are reliable, low-cost and can last for decades with little maintenance. Their main drawback is that they need to be read manually, either by an employee of the local water company visiting the property or by the customer submitting their own readings.
Digital water meters
Digital meters work on the same basic principle as mechanical meters, but the reading is shown on an electronic display rather than a set of rotating dials. Many digital meters still use a mechanical sensor inside to detect flow, while more advanced models use ultrasonic or electromagnetic sensors with no moving parts at all.
The digital display makes readings easier to take and less prone to misreads, particularly for businesses that need to monitor water usage closely. Like mechanical meters, standard digital meters still require someone to take and submit the reading, unless they’re combined with smart meter technology.
Smart water meters
Smart water meters take digital technology a step further by transmitting readings automatically to your water supplier via a wireless network. This removes the need for manual reads and allows usage to be tracked in near real time, making it much easier to spot leaks, monitor out-of-hours consumption and manage water across multiple sites.
Read our full guide to smart water meters to learn more about the benefits and how to get one installed at your business.
Where water meters are located
Water meters are typically installed on the boundary of your property, where a water pipe connects your property to the local water infrastructure.
As the water mains often follow the road network, a common place for water meters is under the pavement outside your property. You’ll be looking for a purpose-built water meter box like this:
Larger properties with more than one water meter or larger meters are likely to be installed in a plant room somewhere inside the building.
If you are still having difficulty locating your water meter, it’s worth contacting your business water supplier, who may be able to look up your meter on the central water market database.
The central database (operated by MOSL) records where meters were first installed; however, these details are often imprecise or incomplete.
How to read a water meter
Taking a manual meter reading is simple. Look at the dial on the front of your meter and record the digits from left to right. These represent the running total of water used in cubic metres since the meter was installed. You can ignore any red digits or numbers after a decimal point, as these usually indicate partial cubic metres and aren’t needed for billing.
Once you have the reading, submit it to your business water supplier along with the date it was taken. Most suppliers let you do this online, through a customer portal, by email or over the phone.
For a full walkthrough with photos, visit our dedicated page on submitting a water meter reading.
Water meter installation
Water meter installations are typically carried out by your local water company on behalf of your business water supplier. For most existing commercial properties, a meter can be fitted free of charge if you request one, and installation is usually arranged within a few weeks.
What to expect during installation:
- Duration: Around two hours from start to finish
- Supply interruption: Typically 30 to 60 minutes while the engineer cuts the pipe and fits the meter, so expect a brief interruption to your water supply during the works
- Process: The engineer excavates a small area at the boundary of your property, accesses your water supply pipe, replaces a short section with the new meter fittings, and installs an underground chamber with a removable lid
- Scheduling: Your water company will usually agree a time slot with you in advance so you can plan around it
- Cost: Free of charge for most existing commercial properties, though larger installations or new connections may involve a quoted fee
For larger commercial properties or higher-capacity meters, installation can take longer and may involve additional groundworks. If you’re arranging an entirely new water supply, read our full guide to business water connections.
Water meter FAQs
Here are our answers to frequently asked questions that we have encountered on water meters in Britain.
What does AMR stand for?
AMR stands for Automatic Meter Reading and refers to any technology that automatically collects consumption data from water meters and transmits it to a central database for billing, troubleshooting, and analysing.
All smart meters use AMR technology, which makes them “smart” and a cornerstone of any IoT (Internet of Things) network as it provides crucial water usage data for decision-making.
Some water companies define “AMR devices” as sensors that can read water meters from a distance. This allows water company staff to take thousands of readings daily by driving slowly on the same road as the water meters.
These devices will soon cease to exist, though, as they are replaced by fully-wireless smart meters.
Is my water meter faulty?
If you suspect that your water meter may be faulty and giving inaccurate meter readings, we suggest considering a water audit.
In a water audit, experts will analyse the historical consumption of water and meter readings at your property to determine if there is a problem. A site visit will follow, where an expert can physically inspect and test the meter.
Where a faulty meter has been identified, we can help you reclaim over-charging from your supplier for up to five years.
Are water meters compulsory?
For households, this depends on your area. In the British water industry, water wholesalers can choose to install meters in their network.
In practice, most commercial properties have a water meter. Around 5% of businesses operate under an unmeasured water tariff, and these are usually the cases where the cost of installing a water meter is prohibitive.
In the household water market, the picture is much more mixed. Some wholesalers are rolling out a universal metering programme to help them manage the water network.
Legally speaking, a water network operator can insist on installing a water meter if a house:
- uses an automatic watering device (such as a garden sprinkler);
- automatically fills a swimming pool or pond;
- has a large bath;
- uses a reverse osmosis softening unit;
- has a power shower;
- is located in an area of serious water stress.
How often are water meter readings taken?
Your business water supplier should arrange a meter reading every six months, though submitting your own readings more regularly helps keep business water bills accurate, flags vacant-property charges early and makes leaks easier to spot.
According to Ofwat water meter readings should be conducted at least once annually.
What if I don’t have a water meter?
Unmetered properties are charged using either assessed charges (a fixed annual consumption based on property type) or rateable value (a fee tied to the property’s rateable value).
Under the Water Industry Act 1999, you can request a meter and your water company must install it unless doing so is not reasonably practical. Check whether you’d save money with our water meter calculator.
How do business water meters differ from residential meters?
Typically a water meter at a small commercial property will use the same hardware as a residential water meter.
Business water meters can be larger and rated for higher flow rates to handle greater commercial volumes required by some properties.
Larger sites may have multiple meters or water loggers to track usage by department or tenant, and billing is always based on actual consumption.
Why is my water meter still running when no water is being used?
This almost always points to a continuous commercial water leak on your supply, often in places you can’t see, such as underground pipework, toilet cisterns or outdoor taps.
If the meter is moving when everything is switched off, isolate the problem by turning off your internal stopcock: if the meter stops, the leak is inside the property; if it carries on, the leak is on the supply pipe before it enters the building. Either way, it’s worth arranging a water audit to pinpoint the source.
Can a water meter detect a hidden leak inside a property?
Indirectly, yes. Unexplained increases in usage or a meter that keeps ticking when nothing is in use are both strong signs of a hidden leak. Smart water meters make this much easier to catch, as they record usage every 15 minutes and flag continuous overnight consumption.
Why is my water meter reading higher than expected?
Higher readings aren’t always caused by leaks. They can also reflect a change in usage, such as new tenants, increased staff numbers or seasonal demand, an estimated bill being reconciled against actual consumption, or a meter misread by your supplier.
If the figures still don’t add up after reviewing recent usage patterns, a water audit can analyse your consumption history to identify the cause, and where a faulty meter is found, it can help you reclaim overcharges for up to five years.
Do I need to submit readings if I have a smart meter?
No. Smart meters transmit readings to your supplier automatically, so manual readings aren’t typically required. It’s still worth checking the dial occasionally to make sure it matches your bills, and contact your supplier if you spot a discrepancy.
Can multiple properties share the same water meter?
Yes, this is common in multi-tenanted buildings such as office blocks and retail parks, where one main meter measures the water entering the building and costs are split between tenants. Submetering is often used to allocate usage more accurately through service charges or direct billing.
What happens if I cannot access my water meter?
Your supplier will usually send estimated bills until access is arranged, which can lead to over or undercharging once the meter is finally read. Contact your supplier to arrange a visit, and if the meter is consistently hard to reach, they may be able to relocate it.
How are my meter readings sent to my supplier?
There are several methods for transmitting water meter readings to your supplier:
- Your supplier will conduct their own manual reading at least once a year.
- You can submit a meter reading yourself and send it to your supplier via their website.
- If you have a smart water meter, your readings will be transmitted automatically to your supplier.
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