One baby's disposable nappy waste in one year will fill 40 bin-bags.
Approximately 8 million disposables are used in the UK every day. 7.5 million of these end up in landfill sites. The remainder are mostly incinerated as clinical waste, but may also end up as litter at roadsides, in car parks, public toilets, residential areas, beaches and beauty spots.
No-one knows how long the plastic part of a disposable nappy takes to break down, but it is not biodegradable. This is estimated to be 10% of the used disposable (the definition of 'used disposable' includes all solid matter and urine produced by the baby and left in the disposable). That means that part of every disposable ever put into a landfill site is presumably still there.
Ecological footprinting (an experimental method of measuring the overall environmental impact of activities) shows that disposables are over two and a half times worse for the environment than service-laundered nappies, and nearly twice as bad as home-laundered nappies.
Note
Figures from the Edinburgh Real Nappy Project Incentive Scheme's 'Guide to Reusable Nappies'.