A swimming pool without a full time, on-site qualified, trained and competent technical operator (SPTO) should have an On-site Designated Supervisor (ODS). This supervisor should be capable of testing the water quality as required by the PWTAG code of practice and know how to make adjustments as needed to maintain water quality as specified in the CoP. They should also be knowledgeable and competent regarding the operation of the facility in terms as required in the pool’s PSOP for both normal and emergency action plans. The principal aim is to operate plant to maintain the quality of the water and take emergency action.


This document sets out the necessary elements for the training of On-site Designated Supervisors (ODS) to PWTAG standards. The PWTAG Code of Practice is the core document, backed up by the PWTAG book, Swimming Pool Water: treatment and quality standards for pools and spas, the PWTAG Code of Practice and PWTAG updates on
The document is divided into two sections.

  • The syllabus
  • Assessment


This is what people studying for PWTAG-approved ODS qualification should be able to understand and where appropriate demonstrate a practical ability.

a Pollution from bathers – understand the main sources from people:

  • skin scales, sweat, urine, mucus from the nose and chest, saliva, hair, faecal matter, cosmetics, suntan lotion.

b Pollution not from bathers:

  • understand other pollution for indoor and outdoor pools – dust, floating debris, grass, earth (soil/stones), precipitated chemicals, sand from filters, chemical ions produced by chemical reactions in water treatment.

c Pre-swim hygiene: toilets and showers – the value of pre-swim hygiene

d When not to swim – exclusion policies

e Babies and toddlers – swim nappies and limitations

a Know how to start up and close down the main pool circulation in the event of power failure; emergency action required

b Monitor pool water circulation

c Take action to ensure that in the event of pool circulation failure, all chemical dosing ceases

d Check inlets and outlets to the pool for security and safety

a Comparator and/or photometer – demonstrate how to use them for pool chemical tests:

  • I. know where to sample
  • II. testing frequency
  • III. how to test for free chlorine, combined chlorine, pH and TDS.
  • IV. interpreting test results and remedial action b Water treatment:
  • V. understanding the principles of breakpoint chlorination
  • VI. pH value – what it is, measuring and checking
  • VII. alkaline and acidic disinfectants – effect on pH
  • VIII. disinfectant and pH tests – PWTAG CoP and standards
  • IX. understanding routine monitoring requirements including bacteriological testing

a Principles – key requirements when dosing chemicals

b Components – the system design and infrastructure

c Dosing practice – where, when and how

d Bulk storage and day tanks

e Hand dosing in emergencies

f Diluting chemicals – how and when

g Dissolving dry chemicals

h Dose strength – ensuring the dosing strength

i Calibration – checking the dosing rate

j Circulation feeders – what they are and how they work in practice:

  • trichlorinators
  • brominators
  • calcium hypochlorite feeders

k CO2 installation and dosing requirements

l Super-chlorination

a Know how to safely deal with a pool soiling

  • solid faeces
  • runny faeces

b Demonstrate an awareness of the PWTAG CoP and technical note:

  • procedure for medium-rate filters
  • procedure for high-rate filters
  • prevention

a Know how to deal with blood or vomit in the pool water

b Demonstrate an awareness of the PWTAG CoP and technical note

To be PWTAG recognised the ODS qualification may only be delivered and assessed by a trainer who has met the criteria as a PWTAG SPTO Accredited Trainer.

The method and means of both delivery and assessment of the ODS qualification shall be set out by the prospective training organisation and included as part of their assessment to become PWTAG Accredited Trainers.

The administration of delivering and assessing the SDO course and qualification shall accord with the requirements for PWTAG Accredited Training providers.