What pence per cubic metre means

A cubic metre is a unit of volume. One cubic metre of water is 1,000 litres, roughly the amount in a large domestic bathtub filled around twelve times over. Your water meter records how many cubic metres flow through it, and the p/m³ rate is what you pay for each one.

So if your rate is, say, a set number of pence per cubic metre and your meter clocks up 500 cubic metres in a quarter, the volumetric part of your bill is simply 500 multiplied by that rate. It is the most direct link between what you use and what you pay.

There are usually two of them

Most business bills carry not one p/m³ rate but two. One covers the clean water supplied to your premises. The other covers wastewater, the cost of taking used water away and treating it. The wastewater rate is often charged on the assumption that most of the water you bring in eventually leaves as effluent, which is why both rates tend to move together on your bill.

If your business uses a lot of water that doesn’t return to the sewer, for example water that ends up in a product or evaporates, you may be paying a wastewater rate on volume that never reaches the drain. That is what a return to sewer allowance is designed to correct.

What the rate is actually made of

The p/m³ you pay isn’t a single figure plucked from the air. It is built mostly from a wholesale charge, set by the regional wholesaler that owns the pipes and treatment works in your area. That wholesale element is regulated and broadly the same whichever retailer bills you. On top of it sits your retailer’s margin, the part they actually compete on.

This is the bit that catches people out. When you switch supplier, you aren’t changing the wholesale cost of the water, you are changing the margin added to it. The savings are real, but they come from the slice the retailer controls, not from the underlying rate the wholesaler charges everyone.

Pence per cubic metre isn’t your whole bill

The volumetric rate sits alongside a standing charge, a fixed daily or annual amount you pay regardless of how much water you use. A headline p/m³ rate can look cheap while a high standing charge quietly pushes the total back up, so it is worth looking at both together rather than judging a contract on the unit rate alone.

For a low-use business, the standing charge can be the larger share of the bill. For a heavy user, the p/m³ rate dominates. Knowing which camp you fall into tells you where to focus when you compare.

Why the rate matters when you compare

Because the wholesale cost is fixed, two quotes for the same site differ mainly on margin. A small difference in p/m³ might look trivial, but multiplied across thousands of cubic metres a year it adds up. Reading your current rate off your bill, then comparing it like for like against an offer, is the single most useful check you can do.

How pence per cubic metre shows up on your bill

Pence per cubic metre, often written as p/m³, is the volumetric rate. It’s the price you pay for each cubic metre of water you actually use. It sits alongside a fixed standing charge, so your bill is really two things added together rather than one flat rate.

Knowing which part is which matters when you’re checking a bill. The volumetric rate moves with how much you use. The standing charge doesn’t. The way these combine is set out on our business water rates page.

Working out your cost per cubic metre

Take the volumetric charge on your bill and divide it by the number of cubic metres used over the same period. That gives you a clean figure for what each cubic metre is costing you, stripped of the standing charge.

It’s a useful number to carry around. Once you know your real p/m³, comparing it against what you’d pay elsewhere becomes straightforward, and you can compare business water suppliers on a like-for-like basis instead of guessing.

Why your rate per cubic metre varies by region

Two businesses using identical amounts of water can pay different rates per cubic metre. A lot of that comes down to the regional wholesaler, whose charges are set locally and feed into your price before any retailer is involved.

On top of the wholesale cost sits the retailer’s margin, and that part is open to negotiation. It’s rarely a huge figure on a single site. Across several sites and a few years, it’s the bit that quietly adds up.

Pence per cubic metre FAQs