You can test for hard water at home in about five minutes. Four methods work. None of them needs a plumber or a lab. Look for the signs. Shake soap in a bottle. Dip a test strip. Then check your water retailer’s data.
This guide walks through all four ways to test water hardness. It also shows how to read your number against the Australian guidelines.
Hardness counts the calcium and magnesium dissolved in your tap water. Utilities report it in mg/L (as calcium carbonate). Some write it as ppm. Both mean the same thing.
How do you test for hard water at home?
Four home methods work. Check your kettle, showerhead and glassware for white scale. Shake tap water with pure liquid soap and watch the lather. Dip a water hardness test strip for a number in mg/L. Then confirm it against your water retailer’s published data.
Each method answers a different question. Pick the one that matches what you need.
| Method | Time | What it gives you |
|---|---|---|
| Household signs | 2 minutes | Hard or not hard |
| Soap test | 2 minutes | Hard or soft, with no number |
| Test strip | 1 minute | A number for your tap, today |
| Retailer data | 5 minutes | Your supply zone’s average, over a year |
Run the strip test and the retailer check together. Most guides tell you to pick one. The strip reads what came out of your tap this morning. The retailer figure reads what your zone averaged over a year. When the two disagree by a lot, look at your own plumbing first.
Method 1: Look for the signs around your house
Your house shows hard water before any test does.
Check these five spots:
- Inside your kettle. A white chalky lining is calcium carbonate. Heat drops the minerals out of the water, so the kettle shows it first.
- Your showerhead. Crusty white deposits sit on the nozzles and around the face plate.
- The shower screen and tiles. Hard water dries and leaves white spots. Plain water won’t wipe them off.
- Glasses out of the dishwasher. Cloudy film on clean glassware is a mineral deposit, not dirt.
- Around the base of your taps. A white powdery ring builds up where water sits and dries.
Three or more of these together means your water is hard. You don’t need a second test to act on it.
One sign on its own proves less. A single scaled kettle can come from a hot water system, not from your supply. Look for the pattern across the house.
Those white deposits started as calcium and magnesium in your water. They came out of solution as the water dried. Our guide explains what makes hard water hard and where the minerals come from.
Method 2: The soap test
This is the fastest do-it-yourself test. It takes about two minutes.
What you need: a clean clear bottle with a lid, pure liquid soap and tap water.
Steps:
- Fill the bottle about one third with cold tap water.
- Add 10 drops of pure liquid soap.
- Put the lid on and shake hard for 10 seconds.
- Stand the bottle down and look at it.
What the result means:
Cloudy water with very few bubbles means hard water. The calcium grabs the soap and kills the lather. A thin grey scum on top is soap scum forming in front of you.
Clear water under a thick layer of white foam means soft water.
One detail decides this test. Use pure soap, not dishwashing liquid. Dish liquid holds detergents that still foam in hard water, so it hides the result. Pure castile soap or a plain soap flake works best.
The soap test gives you hard or soft. It gives you no number. For a number, use a test strip.
Method 3: Water hardness test strips
A test strip reads your hardness in mg/L, or ppm. It’s accurate enough to act on at home.
Steps:
- Fill a clean glass with cold tap water from the kitchen.
- Dip the strip for the time on the pack, usually 3 to 5 seconds.
- Lift it out and hold it flat. Don’t shake the water off.
- Wait for the pack’s colour time, usually 15 to 30 seconds.
- Hold the strip next to the chart on the packaging.
Three things throw a strip reading off. Bathroom light changes the colour you see, so read it in daylight. Hot water changes the chemistry, so use the cold tap. Old strips drift, so check the date on the tube and keep the lid shut tight.
Run the strip on the kitchen cold tap first. That line is closest to the main coming into your house.
Method 4: Check your water retailer’s data
Your water retailer publishes hardness for your supply zone. Your water bill names your retailer. Start there.
Bulk water wholesalers are a dead end here. Melbourne Water and Seqwater sell treated water to retailers. Neither one publishes hardness suburb by suburb. Older versions of this page sent readers to both, and that was wrong.
Where to look:
- Perth and WA: Water Corporation publishes yearly data tables by region. Pick your region, then open the aesthetic data tables. Hardness sits in the aesthetic set, not the health set.
- Adelaide and SA: SA Water runs a postcode tool called Your drinking water profile. Type in your postcode or suburb.
- Melbourne: go to your retailer, not to Melbourne Water. Yarra Valley Water covers the east and north. South East Water covers the south east. Greater Western Water covers the west and north west.
- Sydney: Sydney Water publishes drinking water quality results and a water analysis for your area.
- Brisbane and south east Queensland: Urban Utilities covers Brisbane, Ipswich, Lockyer Valley, Scenic Rim and Somerset. Unitywater covers Moreton Bay, the Sunshine Coast and Noosa. Logan Water covers Logan.
Urban Utilities lists total hardness by supply scheme in its yearly report. Its 2023-24 report ran from 50 to 200 mg/L across twelve schemes. One scheme can read four times higher than another under the same retailer.
Read the zone figure as an average, not as your street. Hardness also moves with the season and with the source your retailer runs that month. For the city-level picture, see our guide to water hardness by postcode in Australia.
Which water hardness test kit should you buy?
Three kit types exist. Strip kits give a colour band in seconds. They suit most homes. Drop kits count reagent drops until the water lathers. A TDS meter measures dissolved solids, not hardness. We don’t sell test kits, so this section is advice only.
Strip kits. You get a tube of strips and a colour chart. Hardware stores, pool shops and online sellers all stock them. Buy strips made for drinking water, not for pools. Pool strips read calcium hardness on its own. They miss the magnesium.
Drop kits, also called titration kits. You add a reagent drop by drop and shake until the water holds a lather. The drop count converts to mg/L. These read closer to a lab figure than a strip does. They take about five minutes and need a steady hand.
TDS meters. A TDS meter reads total dissolved solids in ppm. That total mixes salts, minerals and metals. Calcium and magnesium are only part of it. A high TDS reading in a desalinated supply can come from sodium. A TDS meter is the wrong tool for hardness.
Lab testing. Some water labs test a posted sample and send back a report. This is worth it for bore water and rainwater tanks, where no utility publishes anything.
Match the kit to the decision. A strip is enough to work out whether you need a filter. A drop kit or a lab makes sense before you spend money on whole-house equipment.
What does your water hardness result mean?
Australia measures hardness in mg/L (as calcium carbonate). The Australian Drinking Water Guidelines set four bands. Under 60 mg/L is soft, and it can be corrosive. From 60 to 200 mg/L is good quality. From 200 to 500 mg/L, scaling problems grow. Above 500 is severe.
| Hardness (mg/L as calcium carbonate) | What the guidelines call it |
|---|---|
| Under 60 | Soft, but possibly corrosive |
| 60 to 200 | Good quality |
| 200 to 500 | Increasing scaling problems |
| Over 500 | Severe scaling |
Source: the Australian Drinking Water Guidelines hardness fact sheet, published by the NHMRC.
The 200 mg/L mark is an aesthetic guideline. It’s there to keep scale out of hot water systems. It’s not a health limit, and hard water is safe to drink. SA Water says the same in plain words. More than 200 milligrams per litre counts as hard water.
You’ll see a different scale on test strip packs and on many water websites. It calls 61 to 120 mg/L moderately hard. It calls 121 to 180 mg/L hard. Above 180 mg/L is very hard. That’s the US Geological Survey scale, and the industry copies it. The Australian guidelines don’t use those words at all. So treat it as an industry scale, never as the ADWG.
Both scales can be true about your water at once. A reading of 150 mg/L is hard on the industry scale. The Australian guidelines call it good quality. Scale on your kettle behaves the same either way.
Perth holds the highest published readings in the country. Two Rocks averaged 228 mg/L in the Perth aesthetic tables for 2024-25. That sits in the guideline band where scaling problems grow.
Our guide compares soft and hard water across the home, the body and your appliances.
Your number tells you what to fix, and where. We make hard water solutions for the bathroom. That’s where most people notice hardness first.
What should you do if your water is hard?
You have two main fixes. A whole-house softener uses ion exchange to remove calcium and magnesium from every tap. It needs a plumber, a drain and salt. A shower filter treats water at one tap. It reduces chlorine, heavy metals and sediment, and it reduces calcium and magnesium.
A softener is the thorough option. It’s also the expensive one, and it’s a plumbing job. Renters can’t fit one. The salt refills keep coming.
A shower filter screws in between the shower arm and the showerhead. There’s no plumbing and no tools. The cartridge runs 2 to 6 months in typical home use. The manufacturer rates our multi-stage cartridge at about 38,000 litres (10,000 US gallons).
A shower filter improves water quality. It isn’t a medical treatment for eczema or any skin condition.
For skin and hair, the shower is where hardness shows up first. That’s the tap most people treat. We sell one shower filter in Australia, and it fits standard 1/2-inch shower arms.
Test first, then decide. A number in mg/L turns a guess into a decision.
Tested hard and want the shower sorted first? See POWERBOX Australia for our hard water range.
Last reviewed September 2026 by Lena Hartman
A shower filter is not a medical treatment for eczema or any skin condition. If you have a diagnosed skin condition, consult a dermatologist.
Data note: every figure on this page names its source and its year. Water utilities publish new reports each year. Open the linked source for the newest number before you act on it.
Frequently asked questions
Can you test for hard water with soap?
Yes. Put tap water in a clear bottle, one third full. Add 10 drops of pure liquid soap. Shake it for 10 seconds. Cloudy water with few bubbles means hard water. Lots of white foam means soft water. The test gives you a yes or no, not a number.
What are the signs of hard water in your home?
White chalky scale inside your kettle. Crusty deposits on the showerhead nozzles. White spots on the shower screen. Plain water won’t wipe them off. Cloudy glasses out of the dishwasher. Powdery residue around tap bases. Soap lathers poorly. Three or more of these point to hard water.
What hardness level counts as hard water in Australia?
The Australian Drinking Water Guidelines call 60 to 200 mg/L good quality. From 200 to 500 mg/L, scaling problems grow. SA Water puts it plainly. It treats more than 200 milligrams per litre as hard water. The guidelines use no moderately hard or very hard bands.
Can I use a pool test strip to test water hardness?
A pool strip reads calcium hardness only. Total hardness counts calcium and magnesium together. So a pool strip gives you a rough number, and it reads low. Use a drinking water hardness strip instead. It reads total hardness, and that’s the figure your water retailer publishes.
Does a TDS meter measure water hardness?
No. A TDS meter reads total dissolved solids in ppm. That covers salts, minerals and metals together. Calcium and magnesium are only part of the total. A high TDS reading can come from sodium instead. Use a hardness strip or a drop kit for a hardness number.
Where do I find my suburb’s water hardness in Australia?
Go to your water retailer, not to the bulk water wholesaler. SA Water takes a postcode and returns your water profile. Water Corporation publishes yearly tables by locality. In Melbourne, use Yarra Valley Water, South East Water or Greater Western Water. In Queensland, use Urban Utilities, Unitywater or Logan Water.