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Scald risk in social housing can be reduced through thermostatic control system without increasing Legionella risk: a cluster randomised trial
  1. P Edwards1,
  2. MA Durand2,
  3. M Hollister3,
  4. J Green2,
  5. S Lutchmun4,
  6. A Kessel5,
  7. I Roberts1
  1. 1Faculty of Epidemiology and Population Health, London School of Hygiene & Tropical Medicine, London, UK
  2. 2Faculty of Public Health and Policy, London School of Hygiene & Tropical Medicine, London, UK
  3. 3Department of Housing & Adult Social Care, London Borough of Camden, London, UK
  4. 4Public Health Department, NHS Camden, St Pancras Hospital, London, UK
  5. 5Department of Social and Environmental Health Research, London School of Hygiene & Tropical Medicine, London, UK
  1. Correspondence to Dr Phil Edwards, NPHIR, Faculty of Epidemiology and Population Health, London School of Hygiene & Tropical Medicine, Keppel Street, London WC1E 7HT, UK; phil.edwards{at}


Objective To quantify the effects of a thermostatic control system in social (public) housing on the prevalence of dangerous (>60°C) water temperatures and on fuel consumption.

Design Pair-matched double-blind cluster randomised controlled trial.

Setting Social housing in a deprived inner-London borough.

Participants 150 households recruited as clusters from 22 social housing estates. Four small estates were combined into two clusters (resulting in a total of 10 pairs of clusters).

Intervention Social housing estate boiler houses were randomised to a thermostatic control sterilisation programme (heating water to 65°C during 00:00–06:00 h and to 50°C from 06:00 to 00:00 h daily) or to standard control (constant temperature 65°C).

Main outcome measures Water temperature over 60°C (‘dangerous’) after running taps for 1 min and daily fuel consumption (cubic feet of gas).

Results 10 clusters (80 households) were allocated to the sterilisation programme and 10 clusters (70 households) to control, of which 73 and 67 households, respectively, were analysed. Prevalence of dangerous (>60°C) hot water temperatures at 1 min was significantly reduced with the sterilisation programme (mean of cluster prevalence 1% in sterilisation programme group vs 34% in control group; absolute difference 33%, 95% CI 12% to 54%; p=0.006). Prevalence of high (>55°C) hot water temperatures at 1 min was significantly reduced (31% sterilisation vs 59% control; absolute difference 28%, 95% CI 9% to 47%; p=0.009). Gas consumption per day reduced more in the control group than in the sterilisation programme group, although not statistically significantly (p=0.125).

Conclusions The thermostatic control with daily sterilisation was effective in capping hot water temperatures and therefore reduced scald risk. Although expected to save energy, fuel consumption was increased relative to the control group.

Trial registration ID: NCT00874692

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  • Funding This work was undertaken by the London School of Hygiene & Tropical Medicine who received funding from Camden Primary Care Trust (PCT). AK was Director of Public Health at Camden PCT at inception of the study and assisted with study design and writing of the report. He is currently employed by the Health Protection Agency as Director of Public Health Strategy. The views expressed in the paper are those of the authors and do not necessarily represent those of Camden PCT or the Health Protection Agency. Camden PCT had no role in data collection, data analysis, or data interpretation.

  • Competing interests None.

  • Ethics approval Ethical approval for the study was obtained from the London School of Hygiene & Tropical Medicine Research Ethics Committee.

  • Provenance and peer review Not commissioned; externally peer reviewed.