Wound Irrigation in Prolonged Field Care: Potable Water vs. Normal Saline

In prolonged field care (PFC) scenarios, where medical evacuation may be delayed for days and resources are limited, selecting an effective wound irrigation solution is crucial to prevent infection and promote healing. Potable water, compared to normal saline, is a practical choice for acute wound irrigation in austere environments due to its accessibility and supporting evidence. This article explores the efficacy, benefits, challenges, and practical considerations of using potable water in PFC settings, with practical examples, including improvised irrigation devices, to guide field providers.

Efficacy and Safety of Potable Water vs. Normal Saline

Research supports potable tap water as a viable alternative to normal saline for wound irrigation. A comprehensive analysis of studies involving 1,328 adults found a slight, non-significant reduction in wound infection rates with tap water compared to normal saline. Another trial with 663 participants showed no significant difference in infection rates, with a trend toward fewer infections in the tap water group. A 2023 review confirmed these findings, noting that six out of seven studies reported comparable infection rates between tap water and normal saline, with no increased wound contamination from tap water.

In PFC, where sterile saline may be scarce, these findings highlight potable water’s comparable efficacy and safety for cleansing acute wounds. The Wilderness Medical Society (WMS) Clinical Practice Guidelines recommend potable water as the preferred solution for wound irrigation in wilderness settings due to its availability and strong supporting evidence.

Practical Advantages in PFC

1. Availability and Logistics: Carrying large volumes of sterile saline (1–9 liters depending on wound severity) is impractical in austere environments. Potable water, sourced from treated groundwater or purified on-site, is more accessible. Studies on water purification methods show that chemical purification, filtration/UV purification, or boiling can produce sufficient potable water for both hydration and wound irrigation.
2. Cost-Effectiveness: Tap water is significantly cheaper than normal saline, allowing providers to prioritize other critical resources in PFC where resupply is limited.
3. Volume Requirements: The WMS guidelines recommend at least 1 liter of irrigant for minor wounds, 4–8 liters for moderate wounds, and 9+ liters for severe or heavily contaminated wounds. Producing these volumes is more feasible with potable water using high-throughput purification methods like chemical purification or high-capacity filtration (2.5 L/min).
4. Patient Satisfaction: Some studies report higher patient satisfaction with tap water irrigation, possibly due to its less clinical feel or reduced stinging compared to saline, improving compliance in PFC settings.

Challenges and Considerations

1. Water Quality: Ensuring water potability is critical to avoid introducing pathogens like Pseudomonas spp. Purification methods such as chemical purification, filtration/UV purification, or boiling effectively reduce bacterial loads, though none comprehensively address viruses, protozoa, or toxins. Boiling is the gold standard but requires fuel and time, which may be limited. Chemical purification is lightweight and effective, while filtration/UV methods are faster but less reliable in turbid water.
2. Wound Type and Context: Evidence primarily supports tap water for acute, superficial wounds. For chronic wounds, data are limited, with one study showing a non-significant decrease in infection rates. In PFC, where wounds may become chronic due to delayed evacuation, providers must monitor for infection and consider wound complexity, such as open fractures requiring high-pressure irrigation (6–12 psi).
3. Technique and Additives: High-pressure irrigation (6–12 psi) is essential to remove bacteria and debris and can be achieved with improvised devices like syringes or other field-adapted tools. Additives like povidone-iodine or antibiotics are not recommended, as they offer no proven benefit and complicate logistics.
4. Delayed Care: In PFC, wounds may require repeated irrigation over days. Producing large volumes of potable water daily (e.g., via high-capacity filtration or boiling) is critical, especially for heavily contaminated wounds. Providers must balance water needs for irrigation and hydration.

Practical Recommendations for PFC

• Water Purification: Use lightweight, versatile systems like chemical purification or high-capacity filtration for rapid production of potable water. Boiling is reliable but resource-intensive, so reserve it for fuel-abundant situations.
• Example: In a remote patrol with limited gear, a medic uses chemical purification to treat 5 liters of stream water in 30 minutes, providing enough for both wound irrigation and team hydration.
• Irrigation Protocol: Apply at least 1 liter of potable water for minor wounds, scaling to 4–9 liters for moderate to severe wounds. Use high-pressure irrigation (6–12 psi, comparable to the pressure from squeezing a standard bike tire pump with moderate force) with improvised tools like syringes, perforated water bags, or modified plastic bottles.
• Example: For a laceration on a soldier’s arm, a provider uses a 60-mL syringe filled with potable water from high-capacity filtration, delivering high-pressure irrigation by repeatedly refilling from a 1-liter water bag to achieve 2 liters total volume. The syringe is pushed with enough force to mimic the pressure of a firm squeeze on a bike tire pump, ensuring 6–12 psi to dislodge debris.
• Improvised Device Example: In the absence of a syringe, a medic punctures a plastic water bottle cap with 5–6 small holes (1–2 mm) using a heated needle, fills the bottle with potable water, and squeezes it firmly to produce a high-pressure stream (6–12 psi) for irrigating a contaminated wound. Alternatively, a clean zip-lock bag with a small corner cut off can be squeezed to achieve similar pressure for irrigation.
• Layered Approach: Combine purification methods (e.g., filtration to reduce turbidity, followed by UV or chemical purification) to ensure water safety, especially in turbid sources. Pre-filtering with a 0.2-micron filter is essential for UV purification methods.
• Example: In a muddy river environment, a medic first uses a cloth pre-filter to remove sediment, then applies a 0.2-micron pump filter, followed by chemical purification to ensure potable water for irrigating a deep puncture wound.
• Monitoring: Regularly assess wounds for infection, as delayed evacuation in PFC increases risk. Clinical judgment is critical due to inconsistent infection diagnosis in some studies.
• Example: A provider checks a wound daily for redness, swelling, or pus during a 3-day delay in evacuation, using potable water irrigation every 12 hours to maintain cleanliness.
• Training: Educate field providers on irrigation techniques, water purification methods, and improvisation of irrigation devices to build confidence in using potable water.
• Example: During pre-deployment training, medics practice assembling a high-pressure irrigation system using a perforated water bottle, a zip-lock bag with a cut corner, or a syringe with potable water, simulating a severe wound scenario in a field exercise.

Caveats and Limitations

• Evidence Gaps: Most studies focus on acute wounds in controlled settings, with limited data on chronic wounds or prolonged care scenarios. Further research is needed for complex wounds in PFC.
• Environmental Factors: Water quality varies by location, and untreated water risks contamination. Rigorous decontamination is essential in austere environments.
• Example: A medic in a desert environment tests local water sources for clarity before purification, avoiding turbid water that could clog filtration systems or harbor undetected pathogens.
• Resource Constraints: Producing sufficient potable water for both irrigation and hydration requires careful planning, particularly for large groups or severe wounds.
• Example: For a team of 10 with multiple casualties, a medic calculates daily water needs (9 liters for a severe wound plus 20 liters for hydration) and prioritizes high-capacity filtration over boiling to conserve fuel.

Conclusion

In prolonged field care, potable water is a safe, cost-effective, and logistically feasible alternative to normal saline for acute wound irrigation, supported by robust evidence showing comparable infection rates. Using high-pressure irrigation (6–12 psi, akin to the force of a bike tire pump) with 1–9 liters of properly decontaminated water (via boiling, chemical purification, or filtration/UV) enable effective wound management in austere settings. Practical examples, such as using chemical purification for rapid water treatment, improvised syringes, perforated plastic bottles, or zip-lock bags for high-pressure irrigation, demonstrate how providers can adapt to resource constraints. A layered purification approach, tailored to resources and wound severity, ensures safety and efficacy, making potable water an essential tool for PFC.

References

• Fernandez R, Griffiths R. Water for wound cleansing. Cochrane Database of Systematic Reviews. 2012;(2):CD003861
• 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;3(1):e001504.
• Holman M. Using tap water compared with normal saline for cleansing wounds in adults: a literature review of the evidence. Journal of Wound Care. 2023;32(8):507–512.
• Quinn RH, Wedmore I, Johnson EL, et al. Wilderness Medical Society Clinical Practice Guidelines for basic wound management in the austere environment. Wilderness & Environmental Medicine. 2014;25(4 Suppl):S118–S133
• Holcomb JB, et al. Evaluation of commercial water treatment methods for decontaminating water used in wound irrigation.