Water Test Strips for Food Processing: Monitoring Water Quality and Sanitiser Concentrations
Water quality is a fundamental food safety concern in any food processing or food service operation. Water is used as an ingredient, a heat transfer medium, a cleaning agent, a cooling medium, and a vehicle for chemical sanitisers — and in each of these roles, its chemical composition and microbial status directly affect food safety and product quality. Water test strips provide a fast, simple, and cost-effective method of monitoring key water quality parameters on-site, without the need for laboratory analysis for routine checks. This article explains the role of water test strips in food processing water quality management, the key parameters they measure, and how to incorporate them into a documented water quality monitoring programme.
Why Water Quality Matters in Food Processing
The relationship between water quality and food safety operates through several mechanisms. Microbially contaminated water used in food processing — whether as an ingredient, during washing of produce, or in cleaning and sanitising equipment — can directly contaminate food with pathogens including E. coli O157:H7, Salmonella, Listeria monocytogenes, Cryptosporidium, and Norovirus. Chemical contamination of water can result in off-flavours and odours in finished products, damage to equipment, and health risks to consumers if residues carry through into food.
Water hardness affects the efficiency of cleaning compounds and sanitisers: hard water requires higher concentrations of detergent to achieve the same cleaning effect, and calcium and magnesium deposits from hard water can accumulate on food-contact surfaces, creating niches for microbial growth that resist cleaning. Chlorine — the most widely used water disinfectant — must be maintained at sufficient concentration to control microbial growth in water supplies and cooling systems, but excessive chlorine can affect flavour in products where water is a direct ingredient.
Regular monitoring of water quality parameters ensures that water used in food processing meets the standards required by food safety legislation and your HACCP plan, and that any deterioration in water quality is detected before it affects food safety or product quality.
Key Water Quality Parameters Monitored with Test Strips
Water test strips for food processing applications are available for a range of parameters. The most commonly monitored include free chlorine (hypochlorous acid), total chlorine, pH, total hardness, alkalinity, and sanitiser concentration — specifically peracetic acid (PAA) and quaternary ammonium compounds (QACs), which are widely used sanitisers in food manufacturing environments.
Free chlorine concentration is the most important single parameter for mains water quality monitoring. UK drinking water regulations (Water Supply (Water Quality) Regulations 2016) specify maximum and minimum free chlorine levels for mains water, and food businesses using mains water are entitled to rely on the water supplier to maintain these standards. However, where water is used in extended distribution systems on large production sites, free chlorine can deplete between the mains connection and the point of use, and on-site monitoring provides evidence that adequate chlorination is maintained at the point where water contacts food or food-contact surfaces.
Sanitiser concentration monitoring is particularly important for operations using peracetic acid (PAA) or QAC-based sanitisers in CIP circuits, spray applications, or rinse tanks. Both types of sanitiser are efficacy-critical at specific concentration windows: too low and microbial reduction is inadequate; too high and food contact surfaces or finished product may be contaminated with excessive sanitiser residues. Test strips calibrated for PAA or QAC monitoring provide immediate, quantitative confirmation that working sanitiser concentrations are within specification.
pH monitoring is relevant in operations where water chemistry affects process performance — including in cheesemaking (pH affects coagulation), brewing (pH affects enzyme activity during mashing), and winemaking (pH affects fermentation and tartrate stability). Water pH also affects the efficacy of chlorine-based sanitisers: hypochlorous acid (the active form of chlorine) is most effective below pH 7, and its efficacy decreases rapidly above pH 8.
Water Test Strips vs. Laboratory Analysis
Laboratory water quality analysis provides the most comprehensive assessment of water quality, covering a full suite of chemical, physical, and microbiological parameters with high analytical precision. It is an essential component of any water quality management programme, particularly for annual water safety assessments, new site commissioning, and investigation of suspected contamination events.
Water test strips fill a different role: they provide rapid, on-site monitoring of specific parameters at frequencies that laboratory analysis cannot cost-effectively support. Where a laboratory analysis might be performed quarterly or annually, test strip monitoring of chlorine concentration and sanitiser levels can be performed hourly, daily, or at the start of each production shift — providing a continuous quality assurance record rather than periodic spot checks.
The appropriate programme combines both: laboratory analysis for comprehensive baseline assessment and investigation, and test strip monitoring for high-frequency operational monitoring of the key parameters that are most likely to vary day-to-day.
Incorporating Water Test Strips into a HACCP Plan
For food businesses operating under HACCP, water quality monitoring should be addressed in the HACCP plan where water quality is identified as a significant food safety hazard at any stage of the process. Typical HACCP water quality control measures include monitoring of incoming mains water chlorine concentration at the point of connection to the site, monitoring of process water used directly in food products, monitoring of sanitiser concentration in CIP circuits and rinse tanks, and monitoring of cooling water used in direct or indirect food contact applications.
Where water quality is designated as a CCP, the monitoring method (test strip type), monitoring frequency, critical limits, corrective action procedures, and record format must all be documented and validated. Test strip monitoring records — including the parameter monitored, the result, the pass/fail determination, the date and time, and the person who performed the test — must be maintained and available for inspection by regulatory authorities and food safety auditors.
Frequently Asked Questions
How often should water test strip monitoring be performed in a food processing facility?
Monitoring frequency depends on the parameter being monitored and the risk assessment for your specific process. Free chlorine in incoming mains water should be checked at least daily in operations where mains water is used directly in food products. Sanitiser concentration in active CIP circuits or rinse tanks should be checked at the start of each use and periodically during extended use. pH of process water used in fermentation or other pH-sensitive processes should be checked at the start of each batch. Your HACCP plan should specify the required monitoring frequency for each parameter at each monitoring point.
Can water test strips detect all types of contamination?
Water test strips for food processing are designed to monitor specific chemical parameters — chlorine, sanitiser concentration, pH, hardness — and do not detect microbial contamination directly. For microbiological water quality monitoring, laboratory analysis using membrane filtration or presence/absence methods is required. Test strip monitoring addresses the chemical quality parameters most likely to vary during normal operations; laboratory analysis addresses the full spectrum of microbiological and chemical hazards.
What action should be taken if a water test strip result is out of specification?
Immediately suspend any food processing operations that use water from the monitored source. Investigate the cause of the out-of-specification result — check the water treatment system, the dosing pump or chemical feed, and the sample point for potential contamination. Repeat the test using a fresh strip to confirm the reading. Do not return to production until the cause is identified, corrected, and the water quality confirmed as within specification. Document the non-conformance and corrective action taken.
Are water test strips suitable for use with seawater or process water in coastal facilities?
Standard water test strips are calibrated for potable water chemistry. Process water with significantly different ionic composition — such as seawater, brine solutions, or highly treated demineralised water — may give unreliable readings with standard strips. Specialist test strips calibrated for specific water matrices are available for some parameters. Consult Temperature Indicators Ltd to confirm the appropriate test strip for your specific water type and application.
How should water test strip results be recorded?
Results should be recorded on a dedicated water quality monitoring log, noting the date and time, the sampling location, the parameter and strip type used, the result obtained (the value, not just pass/fail), the acceptance limit, the pass/fail determination, and the name of the person who performed the test. Where results are out of specification, the corrective action taken should be recorded on the same or an associated form. Records should be retained for the period required by your quality management system and applicable legislation.
About Temperature Indicators Ltd
Temperature Indicators Ltd is a specialist global distributor solely focused on temperature-sensitive labels, tags, and indicators for cold chain monitoring, process validation, and regulatory compliance. With 35 years of experience and operations shipping to over 50 countries worldwide, we supply food manufacturers, pharmaceutical distributors, sterile services departments, and logistics providers with the temperature monitoring solutions they need to maintain compliance. Contact us for expert guidance on temperature monitoring for your application.
Legal Disclaimer
The information provided in this article is for general guidance only. Temperature Indicators Ltd makes no warranties, express or implied, regarding the accuracy or completeness of this content. Product specifications, regulatory requirements, and industry standards may change over time. Always verify current requirements with the relevant regulatory authority and consult a qualified professional before making decisions based on information contained in this article. Temperature Indicators Ltd accepts no liability for actions taken in reliance on information provided here.
- Temperature Indicators Staff
