Water Quality Standards for Swimming Pools
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| Parameter | UK swimming pool guidelines | European Drinking Water Standards | DIN norm | PAWS
pool air & water standard | Comments |
| Water Analysis | | | | | |
| DAP Factor, average for mg Chlorine used per bather per day | no limit but typically 6 to 12 | n/a | no limit, but typically 4 to 6 | <4 with target <2 | new water quality parameter set by Dryden Aqua |
| THM`s (chloroform in water)2 | 100ug/l (rarely checked) | <100 ug/l | < 20 ug/l | < 20 ug/l | see note 1. |
| cyanogen chloride (cyanide) | --- | <50ug/l | --- | < 20ug/l | analysis provided by Dryden Aqua, only local pools to Edinburgh at the moment. |
| Total combined chlorine ( in water) | Less than half the free chlorine level | | <0.2 mg/l | <0.1 mg/l for inorganic trichloramine. <0.5 mg/l for organo-chloramines | water sample should be treated with EDTA to remove metal interference |
| Free chlorine | 0.5 to 3mg/l | | 0.3 to 0.6 mg/l | 0.3 to 0.6 mg/l | |
| chlorine dioxide | | <0.4 mg/l | | 0.05 mg/l | |
| chlorite mg/l | | <0.2mg/l | | <0.7mg/l | |
| chlorate | not defined | | --- | <50 mg/l | chlorate has a low toxic level |
| chloride | not defined | | --- | >100 mg/l | guideline applies to freshwater pools |
| Turbidity | --- | <1.0 ntu | <0.1 ntu | <0.05 ntu | Essential, must always be kept low, in AFM systems with ZPM and APF. Warning 0.05 to 0.1, close pool above 0.1ntu |
| hardness as CaCO3 | 40 to 150 mg/l | 150 to 500 mg/l | --- | 250 to 500 mg/l | calcium and magnesium, important for flocculation performance, reduction of disinfection by-products, grout protection and water stability. |
| colour Pt/Co | | <15 mg/l | | <15mg/l | |
| alkalinity as CaCO3 | 75 to 200 mg/l | | --- | 40 to 150 mg/l | important for pH stability, to minimize combined chlorine and for flocculation. Essential for system stability. |
| sodium | --- | | --- | <100 mg/l | guideline applies to freshwater pools |
| sulphate | | <250 mg/l | | <25 mg/l | guideline, non critical, high levels cause turbidity, gypsum scale, and may damage concrete |
| pH | 7.2 to 7.8 | 6.5 to 8.5 | 6.5 to 7.6 | 6.9 to 7.4 | must be kept in the pH band range. 0.2 pH units above or below range, Amber warning, 0.3 pH units Red warning, 0.4 pH units close pool. |
| aluminum | __ | <0.2 mg/l | >0.05 mg/l | 0.02mg/l to 0.05mg/l | critical parameter for optimum water quality. |
| TDS ( total dissolved solids) | 1000 mg/l above influent water | | --- | <1000 mg/l (recommendation) | guideline non critical |
| Ferrous | | <0.2 mg/l | <0.02 mg/l | <0.01 mg/l | |
| Orthophosphates | --- | | <0.005 | <0.005 | Detection kits are only accurate to <0.01mg/l. test kit development required. Must always be below detection level |
| permanganate value expressed as Oxygen mg/l | --- | | <4mg/l | < 4 mg/l | because there is a low bacterial cell biomass BOD may be higher, leading to higher COD. No health issues. guideline only. |
| dissolved oxygen | --- | >75% sat | --- | 100% +/- 2% of saturation | Guideline useful measurement. measured after the filters, indicates anaerobic conditions, or gas super-saturation. |
| ammonium | | | | <0.1 mg/l | mains water supply under 0.1mg/l, alarm if above 0.5mg/l |
| nitrate | | | | <10mg/l | relatively none toxic chemical, but recommend levels below 10mg/l and close pool above 50 mg/l |
| langelier index | --- | --- | --- | -0.5 to +0.5 | best to be slightly -ve if epoxy grout is used with ceramic tiles or plastic, or stainless steel. for Concrete pools and standard grout the index must be +ve |
| Bacteriological | | | | | |
| total coliforms | <10/100ml | <1 / 100ml | --- | < 1/100ml | bathers must shower before entering pool. |
| Pseudomonas aeruginosa 6 deg C +/- 1 deg C | < 50/100ml | < 1/250ml | < 1/100ml | < 1/250ml | bathers must shower before entering pool, systems must be sanitized... good housekeeping must be applied to keep biofilm under control. Use DryOx |
| Escherichia coli 6 deg C +/- 1 deg C | < 10/100ml | <1/250 ml | < 1/100ml | < 1/250ml | bathers must shower before entering pool |
| Legionella pneumophila 36 deg C +/- 1 deg C | --- | | < 1/100ml | < 1/100ml | can only occur in pools with biofilm |
| CFU ( Colony Forming Units) 37 deg C +/- 1 deg C | --- | <20/ml | < 100 / 1ml | < 10 / 1ml | 10 times lower bacterial levels, than DIN and EEC and UK drinking water standards. Close pool if above 100 /ml |
| RLU, bacteria, endotoxins & exotoxins, by ATP analysis | --- | | --- | <100 RLU/ml | good <100, warning 100 to 250, take action, 250 - 500, close pool >500 |
| Air Quality | | | | | |
| nitrogen trichloride | no limit, up to pool operator COSHH | | | <0.3 mg/m3 | Upper limit 0.5 mg/m3 to be reduced to 0.3 mg/m3.. International analysis service provided by Dryden Aqua. see note 4
|
| chloroform | | | | <0.1 mg/m3 | |
| cyanogen chloride | 0.77 mg/m3 upper 15 min exposure | | --- | <0.05 mg/m3 | analytical techniques still in development by Dryden Aqua. 0.77 mg/m3 is HSE limit upper 15min exposure level. |
| | | reference | | | |
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