Water Treatment Testing – Steam Boilers

Frequent, accurate testing of the water in your steam raising system is vital in order to maintain the water quality and lifespan ofsteam boiler the equipment.

There are various tests and checks needed, most are basic and easy to carry out although some are more complicated. There is no reason why a site team can’t carry out all the tests in-house provided they have the time and the expertise. Most sites opt to carry out the simple, frequent tests in-house and rely on an expert service provider for the more in-depth tests.


Water treatment programmes are an expensive investment – you need the chemical dosing to help prevent corrosion, scale formation and other problems, but it comes at a cost. Unless the chemicals are used correctly and the water chemistry is kept under control, major problems can occur with serious cost implications.


Some tests and checks are needed frequently (daily) simply because with steam boilers, things can go wrong quickly and the consequences can be severe. The priorities are:

  • Water softener – basic checks for power, salt and soft water
  • Boiler water TDS – this checks that the boiler blowdown is working properly
  • Boiler water oxygen scavenger (usually sulphite) – checks that this chemical is dosing properly and corrosion is under control
  • Boiler water pH – this checks that the boiler water is not corrosive
  • Feedtank (hotwell) temperature – check that the water is at 80˚C – 85˚C as this means most oxygen is being removed before the water reaches the boiler


Carrying out water treatment tests can be simple – if you know how.

You can access content online (YouTube etc) but the quality is variable.

If you have a good water treatment service provider, they should be able to provide some basic training (toobox talks) or more in-depth sessions to meet your needs.

Or you could access an external course such as:




boiler water treatment test kit

You can get the testing equipment you need from a number of good suppliers


If you’re not sure exactly what you need, a good supplier will support and advise you.





compli appPart of the cost of your programme is for your provider to produce reports showing test results, summary reports, recommendations etc, and for a system to keep the records in. This should be user-friendly – you need to be able to access this information to manage the system, and you may need to call upon it as evidence of compliance.



Keeping records of all test results is really important as it helps to recognise and diagnose problems before they escalate.

If you are paying for a comprehensive record keeping system – make sure you understand it and can make use of it, otherwise consider a simpler more cost-effective system.



  1. Invest in getting your testing set up properly – get the right training and equipment
  2. Work in partnership with your service provider – decide who is carrying out which tests
  3. Review your results – keep good records and use them to look for problems and potential improvements
  4. Congratulate yourself and enjoy the peace of mind!


This table shows the most common tests you need to carry out. There will be variations based on each system and site, but this is a basic guide. There will also be boiler house checks needed such as checking the salt level in the softener brine tank (LINK TO ARTICLE)

Test Softener Feedwater Steam Boiler Condensate
pH Monthly Daily Daily Monthly
TDS Monthly Daily Daily
Oxygen Scavenger Daily
Total Hardness Daily Daily
Temperature Daily
Alkalinity Monthly Monthly Daily Monthly
Chloride Monthly Monthly Monthly Monthly
Phosphate Monthly
Iron Monthly Monthly Monthly Monthly
Copper Monthly


Further information – British Standards