Measurement
Water hardness test kit
Strips or a drop test that report how hard and how alkaline your water is, which is what every other water decision depends on.
- Type
- Measurement
- What it is for
- Measurement
- Who needs one
- Specialist instrument
- Consumable or kept
- Used up and replaced
- Materials
- Reagent strips, Liquid reagent
- Needs attention
- Retest if your supply changes, or seasonally where supplies are blended.
What it is
Almost every piece of water advice in coffee is conditional on numbers most people do not have. A test kit supplies them cheaply: general hardness, which is mostly calcium and magnesium, and carbonate hardness or alkalinity, which is the water's capacity to neutralise the acids in coffee. The two are different and they do different things in the cup.
How it works
Strips change colour against a scale. Drop-based titration kits are slower and more precise: reagent is added until the sample changes colour, and the number of drops is the reading.
Why people use one
To know whether the water needs anything doing to it, to size a filter cartridge properly, and to set a sensible descaling interval instead of guessing.
What this actually changes
Separated by what it affects, because “improves your coffee” is not something you can act on. Where the evidence is thin or contested, it says so.
Seeing what went wrong
Real differenceConverts 'my water is probably hard' into a number you can act on. Water utilities often publish hardness for a supply area too, which is free and worth checking first.
Taste
No differenceTesting changes nothing. What you do with the result might.
Who it is for
Worth having if
- Anyone about to choose a water treatment approach
- Anyone whose coffee tastes flat and chalky, or thin and sharp, for no other apparent reason
Probably skip it if
- Anyone whose supplier publishes a hardness figure they are happy to rely on
Choosing one
What actually differs between them. No products, no rankings.
- Whether it reports alkalinity separately
- A single hardness number is only half the story. Alkalinity is what buffers coffee acidity, and high alkalinity is the more common cause of flat-tasting coffee.
- Strips or titration
- Strips are quick and approximate; drop kits are more precise and take a minute longer. Either beats guessing.
Cleaning and care
Keep strips sealed and dry; humidity ruins them and they will read plausibly wrong rather than obviously so.
What you could use instead
Your water supplier's published analysis
Free, usually accurate for the area, and not specific to your building's plumbing.
Measures total dissolved solids, which is related to but not the same as hardness or alkalinity.
How to use it
Step-by-step techniques this equipment is part of.
When it goes wrong
Often used alongside
Other equipment this one is used with, or that the same brewing methods call for.
Drinks it appears in
Drinks that name this equipment, or that are brewed by a method requiring it.