In Summary, for those who received tap water irrigation:

Benefits in NNT

  • 97.2% saw no benefit
  • 2.8% were helped by preventing an infection
  • None were helped (infection prevented)

Harms in NNT

  • None were harmed
  • None were harmed

View As:

Source: Fernandez R, Griffiths R. Water for wound cleansing. Cochrane Database Syst Rev. 2012 Feb 15;2:CD003861. doi: 10.1002/14651858.CD003861.pub3. Review. PubMed PMID: 22336796.
Weiss EA, Oldham G, Lin M, Foster T, Quinn JV. Water is a safe and effective alternative to sterile normal saline for wound irrigation prior to suturing: a prospective, double-blind, randomised, controlled clinical trial. BMJ Open. 2013.

Efficacy Endpoints: Prevention of wound infection

Harm Endpoints: None identified

Narrative: Various solutions are available for use in wound irrigation. It has been suggested that normal saline may be preferable because of its isotonicity and sterility. This review examines tap water as an alternative to normal saline for wound cleansing and prevention of subsequent infection.

A Cochrane review, including three studies of adults and two studies of children, compared the rates of acute infection from the use of these two solutions for acute wound cleansing.1 In adults (1,328 participants), there was a nonsignificant decrease in wound infection in the tap water group (relative risk = 0.66; 95% confidence interval [CI], 0.42 to 1.04). In children (535 participants), there was a nonsignificant increase in wound infections in the tap water group (relative risk = 1.07; 95% CI, 0.43 to 2.64). [corrected*]

A double-blind randomized controlled trial published since this Cochrane review found similar results. In the 663 participants studied, there was no difference between those irrigated with tap water vs. normal saline, with a trend toward decreased infections in the tap water group.2

Given the lack of adverse events and the affordability of tap water, tap water should be considered as preferable to normal saline for cleansing of acute wounds.

*Correction: Incorrect NNT calculation. “Tap Water vs. Sterile Saline for Wound Irrigation” review originally published August 1, 2015, incorrectly calculated a number needed to treat statistic for decreasing wound infection with tap water. This error stemmed from the review being inadvertently based on an uncorrected version of the Cochrane review. The box at the top should not have included the line “Number needed to treat = 36 to prevent wound infection,” and under Harms it should have read “None were harmed by using tap water.” In the second paragraph of the Narrative section, the sentences related to this should have read: “In adults (1,328 participants), there was a nonsignificant decrease in wound infection in the tap water group (relative risk = 0.66; 95% confidence interval [CI], 0.42 to 1.04). In children (535 participants), there was a nonsignificant increase in wound infections in the tap water group (relative risk = 1.07; 95% CI, 0.43 to 2.64).” This has since been corrected.

Caveats: In the Cochrane review studies, there was no standardization for wound infection diagnosis across the pooled data. In the case of chronic wounds, a small study found a similar, nonsignificant decrease in infection in the tap water group compared with the normal saline group (number needed to treat = 9; 95% CI, 0.01 to 2.96).3

Interestingly, two studies comparing the use of tap water for wound cleansing vs. no cleansing (one enrolling patients with acute head wounds and the other enrolling postoperative hernia patients caring for their wounds at home) found no difference in infection rates.4,5 However, these studies were small and of moderate quality, and further investigations are needed before these findings can be generalized to a broader group.

Author: Christina Chao, MD and Dan Runde, MD

Published/Updated: September 16, 2015

  1. The Title Bar

    The title bar is color-coded with our overall recommendation.

    • Green: Benefits outweigh risks.
    • Yellow: Unclear risk/benefit profile.
    • Red: Benefits do not outweigh risks.
    • Black: Obvious harms, no clear benefits.
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