pH
How acidic or basic your water is. Mostly a plumbing and taste question rather than a health one.
- Safe range
- 6.5 – 9.5 pH
- Ideal range
- 7 – 7.5 pH
- Measured in
- pH
What it is
pH measures how acidic or basic water is on a scale where 7 is neutral. In drinking water it is judged over a much wider band than in a pool, because the concern is not sanitiser performance but what the water does to pipes and how it tastes.
Why it matters
pH is not itself a health parameter at normal levels, and this is the most commonly misunderstood point about it. Its importance is indirect: acidic water is corrosive, and corrosive water dissolves the metal of the pipes it travels through. The health risk in a low-pH home is not the pH; it is the copper and lead the water picks up on the way to the tap.
How to measure it
If you are on a public supply, your utility's annual report already states this, free and laboratory measured. Test it yourself if you are on a well, if you filter or soften the water, or if the question is about one particular tap.
Your utility's annual water quality report
- How trustworthy
- Reference grade
- Cost
- Free
- Effort
- A few minutes of reading
Every community water system in the US has to publish one each year, free, listing what it found and what the limits are. It is real laboratory data about the water leaving the plant and travelling the mains. What it cannot describe is your own plumbing.
Published for the water leaving the plant and travelling the mains. Real laboratory data, and silent about what your own plumbing and any treatment you own have done to it by the time it reaches a glass.
Where to find it: Your water bill, your supplier's website, or the EPA's index of reports. It is also called a Consumer Confidence Report or CCR.
Digital meter or pen
- How trustworthy
- Dependable
- Cost
- Mid range
- Effort
- Seconds to read, minutes to calibrate
A probe on a handheld body that reads the water electrically and prints a number. No colour to judge, which removes the commonest source of error and introduces a new one: a meter that has drifted looks exactly as confident as one that has not.
A pH pen gives a number rather than a colour, which is what you want if you are comparing before and after a filter.
Watch out: Calibrate with buffer solutions before relying on it, and store the probe wet. Be sceptical of a cheap pen in very pure water: reverse osmosis and distilled water carry so little dissolved in them that the reading wanders and takes a long time to settle.
Where to find it: Online and in pool and aquarium shops. Buy the calibration solution at the same time; a meter without it is a guess with a decimal point.
Test strips
- How trustworthy
- Ballpark
- Cost
- Low cost
- Effort
- Under a minute, wherever you drew the sample
A plastic strip with reagent pads on it. Dip it, hold it level, and match each pad against the chart on the bottle at the time the label tells you to. Most strips read several parameters at once.
Strips sold for drinking water are fine for a coarse answer, and are the cheapest way to find out whether the question is worth pursuing.
Watch out: The narrow-range strips sold for pools and aquariums are easier to read than the wide-range ones sold for testing anything, because most drinking water sits in a small part of the scale.
Where to find it: Pool shops, hardware stores, supermarkets and online, sold both per parameter and as multi-packs. Buy strips made for your kind of water: pool strips and drinking water strips read very different scales for the same chemistry.
Certified laboratory, mail-in kit
- How trustworthy
- Reference grade
- Cost
- Most expensive
- Effort
- Careful sampling, then days or weeks of waiting
You are posted bottles and instructions, you fill them exactly as told, and you post them back. Weeks later a report arrives with figures nobody has to interpret by eye. This is what a result you intend to act on should be built from.
Any full drinking water panel includes pH, so it usually arrives alongside the parameters you actually posted the bottles for.
Where to find it: State-certified drinking water laboratories; your state's certification officer keeps the list, and many public health departments will point you at one.
Taking the sample
For several of these the sample is where the error is, and no instrument recovers from a bad one.
- • Run the tap until the water is cold and steady before filling, unless the question is specifically about water that has been standing.
- • Fill the container to the brim and cap it. pH drifts as a sample sits open and exchanges gas with the air, so a bottle carried around all day is measuring the journey.
Further reading: US EPA: Consumer Confidence Reports, the annual report every community water system publishes
If it is too low
Acidic water is corrosive to plumbing and can leach copper and lead from pipes and solder, often showing first as blue-green staining on fixtures or a metallic taste. Common with well water and rainwater-fed supplies.
- • Look for blue-green staining on sinks and fixtures; that is dissolved copper and a sign the water is actively attacking your pipes.
- • An acid-neutralising filter is the standard fix for a whole property.
- • If your home has any lead solder or lead service line, low pH makes testing for lead a priority rather than a curiosity.
If it is too high
Alkaline water tastes flat, bitter or soda-like, and encourages scale in kettles, heaters and coffee machines. Usually harmless to drink but hard on appliances.
- • Usually a taste and scale nuisance rather than a health matter.
- • Descale kettles and coffee machines more often, or fit a scale filter on appliances that care.
Common questions
Is high pH water bad for you?
At the levels found in normal drinking water, no. Water above about 8.5 tends to taste flat or bitter and causes scale in appliances, but it is not considered a health hazard. The US EPA treats drinking water pH as a secondary standard, an aesthetic and infrastructure concern rather than a health-based limit.
Why is drinking water pH range so much wider than pool pH?
Because they are protecting different things. A pool is held to a narrow band, because that is where chlorine sanitises effectively and the water is comfortable on eyes. Drinking water is judged over a much wider one, because there the concern is pipe corrosion and taste, both of which tolerate far more variation. Each page prints its own band at the top.
Is alkaline water healthier?
There is no good evidence that drinking alkaline water produces the health benefits often claimed for it. The stomach is strongly acidic and neutralises ingested water quickly. Alkaline water is not harmful at typical levels, but it is best treated as a taste preference rather than a health measure.
What is the pH of distilled water?
Pure distilled water is pH 7.0, but it does not stay there. Once exposed to air it absorbs carbon dioxide and drifts acidic, typically settling around 5.5 to 6.5. This is normal and is not a sign of contamination; distilled water has almost no alkalinity, so it has nothing to resist the change.
WiseWaterGauge helps you record and understand your own readings. It is not a substitute for a certified laboratory test, and nothing here is medical or regulatory advice. If a health parameter is out of range, confirm it with an accredited lab and speak to your water provider.