High-basicity aluminum chlorohydrate (ACH) is one of the most efficient coagulants available to Australian drinking-water utilities, and choosing it well helps ensure clean, safe, guideline-compliant water at the lowest practical cost. ACH delivers more than 23% Al2O3 and 82-85% basicity, so it neutralises the negative charge on suspended particles and natural organic matter with a low dose and only a negligible change in pH. In a country that follows the Australian Drinking Water Guidelines (ADWG) and a framework of state health regulation, that predictability and low residual load matter enormously. This guide explains what ACH is, why its high basicity suits potable-water treatment, and how to select, dose and monitor it in Australian water-treatment plants. Whether a utility treats river water, reservoir storage or groundwater, correctly applied ACH improves clarity, supports disinfection and helps keep every parameter within guideline limits. It also blends well with organic polymers for difficult, high-colour waters.

Aluminum chlorohydrate (ACH) is a highly polymerised, water-soluble aluminium coagulant with the formula Al2(OH)5Cl·2H2O and a molecular weight of 210.48 g/mol. It is the most concentrated and most highly polymerised member of the polyaluminium family, and it is supplied as a clear to slightly turbid liquid for water-treatment duty.

Typical properties (liquid, water-treatment grade):

Why pre-polymerised matters. Simple coagulants such as alum must first react with the water's alkalinity before they can work, which consumes alkalinity and depresses pH. ACH is already polymerised, so its positively charged species are ready to capture colloids immediately, even in cold or lightly buffered water - a real advantage for Australian rivers and reservoirs that swing in temperature and quality.

Low impurities. Potable-grade ACH is manufactured to tight specifications: iron at 100 ppm or less, very low water-insoluble matter and carefully controlled heavy metals. That low impurity profile keeps residuals small and helps utilities stay within guideline values for metals in finished water.

Blending. ACH can be blended with organic polymers such as PolyDADMAC or polyamine to improve performance in high-colour or high-turbidity events without adding much chemical mass.

Supplied as a clear to slightly turbid liquid, ACH mixes readily and is metered with standard dosing pumps, so no special make-up equipment is required. Because it holds its properties in storage, a utility gets consistent results from the first litre to the last, which matters when plants must respond quickly to changes in raw water.

How ACH compares with other coagulants. Against alum, ACH offers a much higher active concentration and a far higher degree of polymerisation. Against standard PAC products, its basicity and Al2O3 content are higher still, giving stronger charge neutralisation and lower dosing. For utilities weighing chemical cost against dose, sludge and pH correction, ACH frequently delivers the lowest total cost of treated water.

Australian utilities operate under the Australian Drinking Water Guidelines (ADWG), developed by the National Health and Medical Research Council and applied through state health regulators. The framework is preventive and risk-based, and coagulation sits at its core: remove particles, colour and natural organic matter early, and filtration and disinfection downstream perform far more reliably.

Stronger particle and NOM removal. The highly charged, polymerised aluminium in ACH captures turbidity, colour and natural organic matter efficiently. Better NOM removal cuts the precursors that can form disinfection by-products, supporting guideline compliance across a wide range of sources, from Murray-Darling rivers to coastal dams and groundwater.

Minimal pH impact. Because ACH is already heavily neutralised, it barely moves pH, so utilities avoid the cost and complexity of dosing alkali to correct it.

Lower dose, lower sludge. ACH's high Al2O3 content means less product per megalitre, and it produces less water-insoluble sludge, cutting chemical and sludge-handling costs.

Predictable cold-water performance. Pre-polymerised ACH works well in cold water, where alum can be sluggish, giving utilities stable results across the diverse catchments and climates found across Australia.

Low residuals and blend flexibility. In difficult waters, blending ACH with PolyDADMAC or polyamine sharpens performance, while the low iron and tightly controlled heavy-metal content keep finished-water residuals small and predictable.

Regulatory and operational realities reinforce the case. Utilities must demonstrate due diligence under the ADWG and their state drinking-water regulators, and many also report to a local health authority and to the public. A well-specified coagulant that consistently meets its Al2O3, basicity and impurity tolerances makes that compliance easier to prove, especially where a plant blends surface water, groundwater, desalinated water or recycled water.

Total cost of ownership matters too. A higher unit price is easily outweighed by lower dose, fewer deliveries to remote or regional plants, reduced sludge disposal and the avoidance of pH correction - savings that compound over a year of operation.

Cold, low-alkalinity, soft and high-colour waters are all common in Australia, and each punishes a poorly chosen coagulant. ACH's pre-formed polymers handle these conditions with far less trial and error than conventional salts, so operators spend less time fighting coagulation and more time running the plant. For utilities serving small or remote communities with limited chemical-handling capability, a concentrated liquid that doses simply and predictably is a genuine operational advantage.

In short, ACH helps a utility do more with less: fewer chemicals, less sludge and more dependable water quality from a wide range of sources.

ACH is simple to use, but potable-water duty rewards a structured approach. Follow these steps to move from a datasheet to a validated, guideline-compliant program.

Record turbidity, colour, pH, alkalinity, temperature and natural organic matter, and sample across seasons, because floods, droughts and algal blooms all shift coagulation demand. Note any blending of sources and any upstream discharges.

Because ACH is concentrated, start low and bracket upward, comparing performance against your current coagulant on the same water. Measure settled turbidity, floc size and settling rate, then confirm residual aluminium and pH in the treated sample.

Choose a potable-grade ACH that meets your Al2O3, basicity and impurity requirements. For high-colour or high-turbidity events, test a blend with PolyDADMAC or polyamine, adding ACH first under rapid mix and the polymer under slower mixing.

Calibrate metering pumps, set a control range, and monitor treated turbidity, pH and residual aluminium against ADWG values. Automate with online turbidity or streaming-current monitoring where possible, and review the setpoint whenever the source changes.

ACH is supplied in 275 kg drums, 1,350 kg IBCs or a 25 MT flexitank. Keep it sealed in a dry, ventilated place away from rain, heat and sunlight, and never store it with alkaline chemicals such as lime or bleach. Follow the safety data sheet and apply Safe Work Australia WHS practice for chemical handling and dosing.

Consider a regional plant treating a turbid, coloured reservoir source. ACH is dosed ahead of a conventional clarifier and dual-media filters. A jar test sets a low dose on the basis of ACH's high concentration, and operators confirm settled turbidity, residual aluminium and pH against ADWG values. Because ACH barely shifts pH, no alkali correction is needed, and sludge production drops, easing the plant's backwash and lagoon load. In cold winter water, the pre-polymerised chemistry still performs, sparing operators the seasonal dose adjustments that alum would demand.

Do not overdose: because ACH is concentrated, small dosing errors have a larger effect, and excess coagulant can restabilise particles. Match the dose to the source rather than fixing it year round, and always confirm changes with jar tests, since floods and algal blooms shift demand quickly. Where waters are very high in colour or natural organic matter, consider a blend with an organic polymer to hold performance during events, testing it under the same jar-test regime. Finally, never store ACH with alkaline chemicals, and keep dosing equipment corrosion-resistant.

Throughout, keep good records of dose, raw-water quality and treated results, so improvements can be demonstrated to management and, where required, to the drinking-water regulator.

ACH is a well-established potable-water coagulant used by utilities worldwide. In Australia, its use should align with the Australian Drinking Water Guidelines and the requirements of your state drinking-water regulator. Work with a supplier who provides full specifications, impurity data and safety documentation so your authority can confirm suitability for your scheme.

ACH is far more concentrated and highly polymerised than alum. It works at lower doses, produces less sludge, barely changes pH and performs well in cold or low-alkalinity water where alum can struggle. Those advantages often translate into lower total operating cost despite a higher unit price.

Dosages vary widely with raw-water quality, so they should always be set by jar testing on the actual source. Because ACH is so concentrated, its dose is typically much lower than for conventional coagulants; operators bracket upward from a low starting point and confirm performance through settled turbidity and residual measurements.

Very little. ACH is already heavily neutralised, with basicity of 82-85%, so it consumes almost no alkalinity and produces a negligible pH change. That avoids the cost and complexity of dosing alkali, which is why ACH suits waters with limited buffering capacity.

Yes. ACH blends well with organic polymers such as PolyDADMAC or polyamine, which can improve performance in high-colour or difficult waters. Dosage order matters: add ACH first with rapid mixing for charge neutralisation, then the polymer under slower mixing to bridge flocs. Never store ACH with alkaline chemicals.

Store ACH sealed in a dry, ventilated place away from rain, high temperature and strong sunlight, and well away from alkalis such as lime or bleach, which would cause it to fail. Wear suitable protective equipment, avoid skin and eye contact and inhalation, and follow the safety data sheet and local WHS requirements.

For Australian drinking-water utilities, aluminum chlorohydrate offers a rare combination: strong, efficient coagulation, low dose, minimal sludge and almost no impact on pH. Backed by a preventive, risk-based framework under the ADWG, these qualities make ACH a dependable choice across rivers, dams, groundwater and blended supplies. Characterise your source, jar-test the dose, monitor against guideline values and store the product correctly, and ACH becomes one of the most reliable tools in your treatment train - delivering safe, clear water at the lowest practical cost.