What are assessed charges?

An assessed charge, sometimes called an unmetered or rateable-value charge, applies when there’s no water meter at your premises. Instead of billing your real usage, the retailer estimates it, historically from the property’s rateable value or from its size, fittings and likely demand. You then pay that fixed amount whether you use more or less.

Why they often cost more

The trouble with an estimate is that it’s cautious. Assessed charges tend to assume steady, fairly heavy use, so businesses that use water lightly, offices, small shops, low-occupancy sites, frequently pay more than they would on a meter. And because the charge doesn’t move with usage, there’s no reward for using less.

Should you get a meter?

For most low-to-moderate users, a meter is worth looking into. You pay for actual consumption, you become eligible for allowances such as leak and return-to-sewer adjustments, and you get data to spot waste. A meter can usually be requested through your retailer. If your usage is genuinely high and constant the assessed charge might occasionally land in a similar place, but you won’t know until you compare the two.

How an assessed charge is worked out

There’s no meter in the equation, so the retailer estimates your use from fixed features of the property. That usually means its rateable value, its size, the number of taps and toilets, and sometimes the type of business. The two ideas are closely linked, which is why our page on rateable value is worth a read alongside this one.

Because the figure is built on assumptions, it rarely moves. If your real use is lower than the estimate, you keep paying the estimate anyway. That’s the core weakness of assessed billing, and it’s the reason a meter is usually worth looking at.

Switching from assessed to metered billing

If your site can take a meter, moving onto metered charges is often the single biggest saving available. You pay for what you actually use, and the business water rates that apply are based on real volume rather than a flat estimate.

The first step is knowing who currently bills you, which our guide on who your water supplier is covers. After that a meter can be requested, and our business water meters guide walks through what’s involved.

Assessed charges on empty or seasonal sites

Assessed charges tend to hit hardest on properties that sit empty for part of the year. A holiday let, a seasonal unit or a site between tenants still gets billed on the estimate, even when barely any water is being used.

If that sounds like your situation, it’s worth checking whether a meter or a different charging basis would reflect reality better. A quick comparison of your options is a sensible place to start.

A worked example of an assessed charge

Picture a small office with no water meter. The retailer looks at the property’s rateable value, its floor area and its fixtures, then applies the regional unmetered tariff. Out comes a fixed annual figure, split into clean water and wastewater, that lands the same whether the office is full or half empty.

Here’s the part that catches people out. Two near-identical units on the same street can pay different amounts, purely because their historic rateable values differ. Nothing about how much water you actually use comes into it, which is why a meter so often tells a cheaper story.

Assessed charges FAQs