How to choose the best dishwasher detergent

Rinse aid

Rinse aid is an additive that helps water spread evenly over the surface of your dishes, making droplets less likely to form and leave spots, while also hastening drying. Many tablets and capsules claim to contain rinse aid; while powders often don’t have rinse aid, as it needs to be released at a certain point in the wash.

A popular substitute for rinse aid is white vinegar, but we don’t recommend using this as it can cause damage to the rubber seals and gaskets in your dishwasher, costing you in repairs in the long run.

Septic tanks

Some products claim to be safe for septic tanks, but we’ve found that they often don’t back up this claim, for example by quoting a testing standard. As septic tank designs can differ quite a bit, and using the wrong product can have costly consequences, you should always consult your septic tank’s manual or manufacturer before using a new dishwasher detergent.

Dishwasher cleaners

Dishwashers do a tough job and, while most look nice and clean after a wash, grease and limescale can build up in hard-to-see parts, such as the filters, spray arms, pipes, water pump and drains. While dishwasher cleaning products can help keep your dishwasher sparkling an occasional hot wash when it’s empty can work just as well and won’t cost anything but your time. See our tips on cleaning and maintaining your dishwasher.

Always keep your dishwasher detergent well out of reach of children and keep the packaging so you can quickly identify the product. Medical advice is available 24/7 from the National Poisons Centre (0800 POISON). If someone ingests a detergent, call an ambulance.

To make sure your kids stay safe:

• Store dishwasher detergents well out of the reach of children or in a locked cupboard.
• Only put detergent in the dishwasher when you're ready to start a wash.

Since 2007, dishwasher detergents sold here can’t have a pH above 12.5. With every dishwasher detergent test, we check if they breach this threshold, and none have in many years.

Buying detergent in larger packs often reduces the cost per wash. However, as they’re likely to be stored for longer, this increases the chances of moisture in the air causing tablets to stick together and powder to clump.

To help avoid this, if the manufacturer’s packaging can’t be sealed completely, keep your detergent in an airtight container. Keep the original packaging, as this can help with identification if someone swallows it or the product is recalled.

Phosphates are bad

Phosphates promote algal growth in waterways, which can choke the waterways’ natural vegetation. The good news is that phosphates are no longer necessary in dishwasher detergents. Dishwasher detergents now often rely on enzymes and surfactants instead. As phosphates have stopped being used, a detergent claiming to be “phosphate free” risks misleading consumers, as it is touting a benefit that’s no longer relevant.

Parallel imports

Parallel-imported detergents are often genuine (in other words, non-counterfeit) products brought into the country by a store or distributor without the manufacturer’s permission. For example, Reckitt Benckiser New Zealand owns the Finish brand and supplies most stores, such as supermarkets, with formulas it considers relevant for the New Zealand market. However, some companies import Finish products from other regions in the world.

Parallel-imported products can often be identified because they incorporate multiple languages other than English on their packaging, and place their safety and ingredients information (such as the importer name and National Poisons Centre information) on a sticker instead of printing it on the packaging.

Often a parallel-imported product will have an almost identical name to the one provided by the local distributor, but are likely to have different formulations meaning they’ll perform differently.