A Consumer NZ test of 23 dishwasher detergents has found some products don't clean your dishes significantly better than a cycle with plain water. 

The consumer watchdog tested 16 tablet options and seven powder products - with four washes on six commonly stuck on food grime - against washing with just water. 

Overall, tablets or capsules were found to consistently perform better than powders. 

Performance also came at a cost, according to the test results. 

"While powders are cheaper per wash and there's some level of control over the dose, they still don't clean dishes well. The powder is messy to add to the dispenser and people can get the dosage wrong", said Consumer NZ test content team leader James le Page. 

Powders also often don't contain rinse aid, an additive that helps water spread evenly over the surface of dishes to reduce spots and hasten drying. 

The results 

Consumer NZ gave a "recommend" to 13 products it tested, while three received a "don't buy" warning. 

Two Finish products took out the top spot. Finish Quantum Ultimate Pro Lemon Sparkle ($20 for 32 tablets) and Finish Quantum Ultimate Pro Fresh Burst ($15.99 for 32 tablets) both scored 80 – the highest in the test. 

But both products also came out to average about 63 cents a tablet. 

Active Ultimate Citrus Zest ($10 for 30 tablets) was runner up, scoring 79. Active Rapid Lemon ($10 for 30 tablets) scored 77 and were also both Consumer NZ recommended products. 

Consumer NZ said the two Active products performed well and were good value for money at 33 cents a tablet. 

The top-performing powder came from Active. Its automatic dishwashing powder lime with baking soda ($5 for a 1kg bottle) scored 63. 

Two of the powders and one tablet product received a "don't buy" warning from Consumer NZ. Green Goddess Citrus Dish Wash Powder ($17.95 for 1kg) which scored 15 and Will&Able ecoDish Powder ($11.99 for 1.5kg) which scored 36. They both performed poorly at removing most food stains. 

Necessities Lemon Scent with Baking Soda ($3 for 20 tablets) also received a"'don't buy" and scored 13. 

The water only cycle scored 9 overall for all stains. 

Consumer NZ also assessed safety information provided on the packaging. Almost all products provided critical safety information on the packaging regarding general product safety, first aid advice and poisons centre contact details. However, Green Goddess Citrus Dish Wash powder's first aid advice and poisons centre information was notably absent.