Chemical Dilution Ratios and Dosing Systems

Correct chemical dilution means measuring the exact ratio of concentrate to water shown on the product label, then applying it for the stated contact time. Under-dosing leaves cleaners and sanitisers too weak to lift soil or kill bacteria; over-dosing wastes product, risks chemical residue and taint on food-contact surfaces, and can corrode equipment. Automated dosing systems and pre-measured methods deliver a consistent, verifiable dilution every time. Key takeaways: Dilution ratio and contact time are set by the product label and its Safety Data Sheet (SDS) — follow both, because a sanitiser only works at the concentration it was tested at.. Too weak fails to sanitise; too strong wastes money, corrodes equipment and can leave residue or chemical taint on food-contact surfaces.. Automated dosing dispensers and pre-measured methods remove guesswork and give a repeatable, auditable dilution every shift.. Clean first, then sanitise — sanitisers are deactivated by food soil and grease, so a two-stage process is essential.. Verify concentration with test strips where the chemical allows, and keep dilution and SDS records so staff and auditors can confirm the process.. Why the right dilution ratio matters A cleaning chemical or sanitiser is formulated and tested to work at one concentration. Dilute it too much and it will not remove grease or reduce bacteria to a safe level, leaving surfaces that look clean but are not. Dilute it too little — a common reaction to a stubborn mess — and you waste product, risk corroding stainless steel and seals, and increase the chance of residue transferring to food. Over-strength sanitiser is a particular problem on food-contact surfaces. Residue can taint food with an off taste or smell, and some concentrates are classed as hazardous chemicals under work health and safety law, so higher concentrations raise the risk to staff handling them. Getting the ratio right protects food safety, your equipment and your chemical budget at the same time. Too weak: soil and bacteria remain; sanitising fails silently.. Too strong: residue, taint, corrosion, higher cost and greater handling risk.. Correct: the chemical performs exactly as the manufacturer validated it to.. How dilution ratios and ppm actually work A dilution ratio is written as parts of concentrate to parts of water. A 1:100 dilution means one part chemical to 100 parts water — for example, 10 mL of concentrate made up to roughly one litre of solution. A 1:10 ratio is ten times stronger. Always read whether the label means "parts of water" or "parts of finished solution", as the two differ slightly, and use the manufacturer's figure rather than a rule of thumb. Sanitisers are often specified in parts per million (ppm) of active ingredient rather than a simple ratio, because effectiveness depends on the active concentration, not just the volume of concentrate. The target ppm, the water temperature and the contact time are all set by the product and its SDS. Do not convert or estimate these yourself — follow the label and confirm with test strips where the chemistry allows. Ratio: 1:100 = one part concentrate to 100 parts water.. ppm: the active concentration in the finished solution — check the label for the target.. Never scale a ratio up "to be safe" — stronger is not more effective and can cause residue.. Dosing systems: from measuring jugs to auto-dilution The simplest reliable method is measuring: use a marked jug or a dosing pump that delivers a fixed volume of concentrate per litre of water. Free-pouring "a glug" into a bucket is the single biggest cause of inconsistent dilution and should be avoided. Pre-measured sachets and dissolvable pods are another low-error option for small sites. Automated dosing systems draw concentrate through a wall-mounted dilution-control unit that mixes it with mains water at a preset ratio, filling a bottle, bucket or sink to the correct strength on demand. These reduce staff exposure to concentrate, cut waste and give a repeatable result regardless of who is on shift. Whichever system you use, calibrate and check it periodically — worn dosing tips and blocked venturis drift out of specification over time. Measuring jug or dosing pump — cheap, reliable, needs training and discipline.. Pre-measured sachets or pods — hard to get wrong, good for small operations.. Wall-mounted dilution control — consistent, lower exposure, but must be maintained and checked.. Contact time, water temperature and clean-first sequencing Dilution is only half the job. A sanitiser needs its full stated contact (dwell) time on the surface to work — wiping it off immediately does almost nothing. Let the diluted solution sit for the time on the label before rinsing or drying, and use the water temperature the product specifies, as some chemicals lose activity in water that is too hot or too cold. Sanitisers are also deactivated by food soil, grease and protein. That is why cleaning and sanitising are two separate stages: first wash with detergent to remove visible soil, rinse, then apply the sanitiser at the correct dilution and contact time. Applying sanitiser to a dirty surface wastes the chemical and leaves the surface unsafe. Give the sanitiser its full contact time before rinsing or drying.. Match the water temperature to the label — hotter is not always better.. Clean and rinse first; sanitise second. Soil neutralises sanitiser.. Avoiding residue, taint and corrosion Where a product is not a no-rinse, food-safe-at-that-concentration sanitiser, follow the label's rinse instruction so no chemical remains on food-contact surfaces. Residue is most likely when solutions are made too strong, left to dry as puddles, or applied to surfaces that were never rinsed after detergent. Air-dry or use clean, single-use or laundered cloths rather than wiping residue around with a dirty one. Corrosion is the long-term cost of over-strength or wrongly matched chemicals — chlorine-based sanitisers in particular can pit stainless steel if used too concentrated or left in contact too long. Store concentrates and diluted solutions separately from food, clearly labelled, and never decant chemicals into unmarked or food containers. Whether rinsing is required after sanitising varies by product, so confirm it on the label and SDS. Make solutions at the labelled strength, not stronger, and don't let them dry as puddles.. Rinse where the product requires it; air-dry or use clean cloths.. Label every diluted solution and never store chemicals in food containers.. Records, SDS and staff training Every chemical on site should have a current Safety Data Sheet (SDS) that sets out the correct use, dilution, hazards and first-aid measures, kept where staff can reach it. The SDS and the product label together are your authority for the correct ratio, contact time and any rinse step — train staff to read them rather than rely on memory. Keeping simple records — which chemicals are used where, at what dilution, and confirmation that dosing equipment has been checked — supports your food safety program and helps demonstrate control to an auditor or inspector. Requirements sit within the Food Standards Code (including Standards 3.2.2 and 3.2.2A) and work health and safety law, but specific obligations vary by state and territory, so confirm what applies with your local council or regulator. Keep a current SDS for every chemical, accessible to staff.. Train on reading the label and SDS, correct measuring, and the clean-then-sanitise sequence.. Record dilutions and dosing-equipment checks as part of your food safety program.. Checklist: Current SDS on site and accessible for every chemical. Correct dilution ratio or ppm confirmed from the label, not memory. Dosing pump, jug or automated system used — no free-pouring. Concentration checked with test strips where possible. Surfaces cleaned and rinsed before sanitiser is applied. Full contact time observed before rinsing or drying. Rinse step followed where the product requires it. Diluted solutions clearly labelled and stored away from food. Dosing equipment checked and calibrated periodically. Dilutions and checks recorded in the food safety program. Common mistakes: Free-pouring concentrate "by eye" instead of measuring it. Making sanitiser stronger than the label to "be safe", causing residue and corrosion. Wiping sanitiser straight off instead of allowing the full contact time. Applying sanitiser to a greasy or dirty surface, which deactivates it. Using water that is too hot or too cold for the chemical. Skipping a required rinse and leaving chemical residue on food-contact surfaces. Storing concentrate or diluted solution in unlabelled or food containers. Never checking or calibrating automated dosing units, so they drift out of specification.