Tablets are popular among leading brands but also smaller eco ones. Astonish, ATTITUDE, ecoleaf, Ecover,
Ecozone, Finish, Smol, Sodasan, Sonnet and Splosh all use tablet form.
Tablets are compact, resulting in less carbon emissions from transportation. They’re convenient to use and store.
However, tablets tend to be more expensive than liquids or powders and they often come individually wrapped.
The wrapping of most tablets and pods, including the eco kind, is usually made from polyvinyl alcohol (PVA), a synthetic polymer. Debates appear to be ongoing about how biodegradable PVA is. See the pods section below for more on this.
It appears that dishwasher tablets require a significantly thinner PVA wrapping in comparison with pods, which require a much bulkier casing to contain liquids.
Dishwasher pods - are they bad for the environment?
Pods, also known as packs or liquitabs, are compact, saving on CO2 emissions through transportation and saving space in your cupboard. They’re also generally mess-free. However, like tablets, pods often involve a lot of packaging and are more expensive than alternatives.
The PVA that pods are encased in is promoted as 100% water-soluble and biodegradable. A recent study from March 2021 into PVA used on dishwasher pods stated that it is biodegradable and “there is no concern for persistence or accumulation in the environment.”
But a preliminary study by Arizona State University into the PVA used on dishwasher pods published in April 2021 suggested that "about 4% of the PVA from detergent pods is discharged undigested in treated water, while 65% ends up in sludge” that may end up in landfill, applied to agricultural land or incinerated. The study's author suggests it could harm aquatic ecosystems.
Pods also contain highly concentrated caustic detergent – making them hazardous to children and animals should they be ingested. They are often colourful and look a bit like sweets.
A 2016 article in 'Emerging Medicine News' stated “The thin water-soluble packaging material is fun to touch but easily penetrated by a child's fingers, teeth, and saliva. [...] Unlike the old-fashioned granular and liquid detergents that usually produced only mild irritation, these newer products demand clinical respect and likely a bit more observation time.”
One study showed that in 2012-13, when pods were relatively new, over 17,000 children aged under 6 had been poisoned by the pods; 4.4% were hospitalised, and 7.5% experienced moderate or major medical outcomes.
Due to PVA use, and the risk they cause to health if accidentally ingested, plus the high price tag, pods seem like the least attractive option for dishwasher detergents.
Method offers dishwasher pods. Fairy and Finish sold ‘dishwasher tabs’ which appear to be a combination of a
tablet and a pod (a solid tablet with a liquid capsule on top).