MONEY

How energy and water bills work

Why people get £4,000 energy bills — and how to avoid it

 

We’ve all heard the horror stories: “They received a £4,000 electricity or gas bill.” How does this even happen?

After 15 years working in an energy company, I can tell you exactly why — and how to make sure it never happens to you.

🔌 Old meters don’t send readings

Traditional gas, electricity, and water meters have to be read manually. Now imagine the entire population of your country. Then imagine how many millions of customers each supplier has.

The maths simply don’t work. No supplier can employ enough meter readers to visit every home regularly, also we can do it for free and it is in our best interest to do so.

📉 Suppliers are allowed to estimate

Because the logistics are impossible, suppliers are permitted to estimate your usage. Most people don’t realise this. They assume the bill reflects what they actually used.

But if:

  • you submit readings but they already billed you

  • you don’t submit readings

  • or the meter reader can’t access your property

  • or the meter hasn’t been checked in years

…then the supplier has no real data. They guess. And sometimes they guess wrong — for months or even years.

💡 “I pay £X” doesn’t mean “I use £X”

I always tell people: What you pay and what you use are two different things.

You might be underpaying for years without knowing it. Then one day, the supplier gets an actual reading — and suddenly you owe the difference.

That’s where the £4,000 bills come from.

🧭 How to stay in control

Take your own readings regularly:

  • every 3 months

  • or every month if you want to be extra safe

It takes 30 seconds and can save you thousands.

Once you start tracking your usage, you’ll also understand how suppliers calculate your bills — and you’ll never be caught out by a huge “catch‑up” charge again.

A simple habit that protects you.

Most people don’t get huge bills because they used too much energy. They get huge bills because no one had the correct numbers.

A quick reading every few months keeps you in control — not the estimates.

What people don’t realise when they move into a new home

When you move into a property, you automatically inherit the existing energy supplier. Even if you plan to switch immediately, you still need to:

  • contact the current supplier

  • give them your opening meter readings

  • set up a temporary account

Why? Because suppliers buy energy months in advance for the homes they supply. So even if you switch on day one, they still need to bill you for the energy used before the switch completes.

If you don’t contact them, they will still try to bill you later — sometimes months down the line.

 

🔍 Can they back‑bill you? Yes — but with limits

There is a back‑billing limit in the UK:

  • Suppliers cannot charge you for energy used more than 12 months ago, if the lack of billing was their fault (for example, they didn’t send bills or didn’t follow up).

But if:

  • you never contacted them

  • you didn’t give opening readings

  • you didn’t set up an account

…then the 12‑month protection may not apply, because the supplier had no way to bill you correctly.

So yes — they can track you down and bill you later, and people are often shocked when it happens.

 

How to avoid this completely

When you move in:

  • Take pictures of the meter readings immediately

  • Find out who the current supplier is (there are lookup tools), and any supplier can tell you too

  • Contact them within the first few days

  • Give them your readings and set up an account

  • Then as long as you don't sign up to a tariff with exit fees, you can switch to whoever you want

This protects you from:

  • back‑billing

  • estimated bills

  • being charged for the previous tenant’s usage

  • disputes later

It’s peace of mind for you.