What should specifiers seek when purchasing washer-disinfectors (WDs)? And what tests should products undergo to demonstrate they’re meeting the necessary requirements? 

The newly revised BS EN ISO 15883-1:2025 Washer-disinfectors — Part 1: General requirements, terms and definitions and tests is the first part of the ISO 15883 series. It sets out general requirements applicable to all washer-disinfectors and their accessories to be used for the cleaning and disinfection of reusable medical devices. 

It then details how to test for conformity, the documentation and information that machines should be supplied with, and how they should be marked, labelled and packed. The requirements in Part 1 apply to all washer-disinfectors specified in subsequent parts of the series except where they’re modified or added to by the subsequent part.

Disinfection efficacy

The standard notes that the performance requirements of any given washer-disinfector will depend on a number of factors, including the nature of the items being processed, the nature and extent of any pre-treatment, the nature of the contamination to be removed, the cleaning agent, the permissible extent of process residues, and the disinfection efficacy required (which is related to the level of risk associated with item use). 

The WD’s specified performance is achieved by an operating cycle that, as appropriate, will include stages for cleaning (that can include pre-wash flushing, washing and rinsing stages), disinfection, final rinsing and drying where appropriate.

Disinfection is the process that inactivates viable microorganisms to a level specified to be appropriate for a defined purpose. It can be thermal or chemical. The disinfection temperature is the minimum temperature at which the evaluation of the disinfection efficacy is based, and several disinfection temperatures and holding times can prevail during the disinfection stage. 

Throughout the cycle, the rate and extent of temperature changes, pressure changes or changes in the concentration of process chemicals should be within specified limits. In addition, machines should have a self-disinfection cycle to ensure they don’t become a focus for load contamination and also to disinfect the machine after maintenance, repair or testing.

Mechanical, process and testing requirements

BS EN ISO 15883-1 specifies mechanical and process requirements in relation to materials of construction as well as for design and manufacture. It requires machines to conform with IEC safety requirements and specifies how the tanks that store process water within washer-disinfectors, and the loading and unloading doors should perform.

It covers pipework and fittings, spray and dosing systems and load temperature protection and temperature, as well as pressure, operating cycle and fault indicating equipment and control systems. It also specifies water supply, venting and drainage. 

Then it details how to test for conformity with the requirements of the standard, specifying testing instrumentation and thereafter a comprehensive regime of tests. This includes everything from fault indicators and water quality to cleaning efficacy and load dryness.

An increase in minimum temperature

There are a number of changes in BS EN ISO 15883-1:2025. These include:

• The alignment of terms and conditions with related standards.

• The addition of requirements for load carriers.

• The clarification of water quality requirements.

• An increase in the minimum temperature limit for thermal disinfection.

It's expected that the washer-disinfectors covered by this standard will be used for laboratory, veterinary, dental and pharmaceutical applications and for other specific applications, such as for bedsteads and transport carts and for the disinfection of crockery and cutlery for use with immunologically compromised patients. 

Note it’s the user’s responsibility to ensure the appropriate choice of type of washer-disinfector, operating cycle, and quality of process chemicals for any particular load.

The standard can also be used by prospective purchasers and manufacturers as the basis of an agreement on the specification of a washer-disinfector. The test methods specified in the standard can be employed by users to demonstrate continued conformity of an installed washer-disinfector throughout its service life. It can help improve the efficiency of manufacture and operation of washer-disinfectors and can help increase confidence in the efficacy of washer-disinfectors in operation. 

Finally, this is a standard that can help manage the risks that arise in relation to washer-disinfectors.

Add BS EN ISO 15883-1:2025 to your collection today.