Britain's Best and Worst Places for Brewing Coffee, Revealed

Good coffee starts with good beans. But what about the water?

It makes up around 98% of your brew, yet it's probably the ingredient you think about least. And whether you're brewing a supermarket blend or your favourite speciality coffee, what's coming out of your tap could be having a bigger impact on your morning cup than you realise.

So, we decided to investigate.

We analysed tap water quality across 120 postcode areas in Britain, comparing five key measures against the Specialty Coffee Association's recommended brewing water targets.

The result? Our Coffee Water Index, revealing which parts of Britain have the best (and worst) tap water for brewing coffee.

And let's just say, some of the results surprised us.

Why does water matter so much for coffee?

It's easy to get caught up in grind size, brewing ratios and finding the perfect beans. You might have invested in a decent coffee grinder, experimented with different brewing methods or spent ages dialling in your espresso. But water plays a pretty important role in how those beans actually taste.

Minerals, alkalinity, chlorine and pH can all influence flavour extraction, changing the balance of acidity, sweetness and bitterness in your cup.

"When preparing coffee at home, what comes out of your tap matters just as much as the type of coffee you're using. A lot of the time people dial in grind size and brew ratios, but water is the one variable most people overlook, even though it makes up around 98% of the cup." - Ashlee Eastwood-Quinn, our Head of Coffee.

London loves coffee. Its tap water? Not so much!

London might have one of the country's most exciting coffee scenes, but its tap water tells a rather different story.

All eight London postal districts ranked in the bottom third of our Coffee Water Index, with none reaching the national average score of 57.6 out of 100.

North London performed best of the eight, scoring 47.3, while East London came last at 39.2.

How London's tap water ranks:

Where in Britain has the best tap water for coffee?

If you're brewing coffee in Lerwick, you're in luck.

The Shetland postcode area topped our Coffee Water Index with a score of 84.7 out of 100, thanks to its favourable water hardness, conductivity and low chlorine levels.

Scotland performed particularly well overall, claiming six of the top 10 spots. Meanwhile, Harrogate came out on top for England, scoring 78.9.

The 10 best postcode areas for brewing coffee:

And the worst?

At the other end of the scale, Ipswich ranked last with a score of just 28.9 out of 100.

Its tap water recorded particularly high hardness and alkalinity levels, both of which can affect how coffee flavours are extracted.

Sunderland and Slough also ranked towards the bottom, with high mineral content and conductivity contributing to their lower scores.

The 10 lowest-scoring postcode areas:

So, what if your area didn't score well?

Don't panic. You don't need to move to Shetland to make a decent flat white.

If your tap water isn't particularly well suited to brewing coffee, using filtered water is one of the simplest things you can try. A water filter can help reduce chlorine and, depending on the type, manage some of the minerals that affect how your coffee tastes.

As Ash puts it:

"If you live in one of the postcode areas that performs less well, it doesn't mean good coffee is out of reach. Opting to use filtered water can make a huge difference to the quality of your coffee experience."

Good beans, good technique and a little attention to your water can go a long way.

And if you're looking to give your next brew an upgrade, our coffee subscriptions are a pretty good place to start. Freshly roasted speciality coffee, delivered straight to your door.

You sort the water, we'll sort the beans.

Frequently Asked Questions

How was the Coffee Water Index calculated?

We analysed tap water quality data from MyTapWater.co.uk, covering 66,706 postcodes across 120 postcode areas in England, Wales and Scotland.

We compared five water quality measures against brewing water targets published by the Specialty Coffee Association, then combined the results into a score out of 100.

The closer an area's tap water came to the recommended targets, the higher its Coffee Water Index score.

What water quality factors were measured?

We looked at five factors known to influence how coffee tastes, each given a different weighting in the final score:

The Specialty Coffee Association recommends a target of 150 mg/L for total dissolved solids (TDS). As water companies typically report this information as conductivity, we converted the target to 230 μS/cm for our analysis.

Where did the water quality data come from?

Our analysis used tap water quality data from MyTapWater.co.uk, based on the 25 most populated postcodes in each postcode district.

Where a water company hadn't reported a particular measure, we used a statistical method called mean imputation to fill the gap using an average value.

Does a low Coffee Water Index score mean the tap water is unsafe to drink?

Not at all. The Coffee Water Index measures how closely an area's tap water matches the selected targets for brewing coffee, not whether it's safe to drink.

A lower score simply means the water is further from those targets and may affect how your coffee tastes. It doesn't mean the water is unsafe or unsuitable for everyday drinking.