Cloth diapers reduce your family's impact on the environemt, period. Yes, cloth diapers require washing, but once a cloth diaper is made, it can potentially last several children. More water is required in the manufacturing process of a disposable than in a cloth diaper, and much more than a simple wash of a cloth diaper.
If your child is completely potty trained by 24 months, she will require on average 6,000 diaper changes. That is approximately one ton of garbage! Disposable diapers take approximately 500 years to decompose, and we don't even know if they ever fully decompose since there are so many plastics and plastic byproducts in them.
No mater your diapers system, parents are supposed to remove solids prior to disposal, but parents using disposables rarely remove solid waste. All this solid waste, full of bacteria, viruses and vaccines, also ends up in the landfill. Now your baby's poop becomes a threat to wildlife as well as out entire ecosystem.
Thi is just the diapers, not to mention all the plastic packaging, the disposable wipes, the disposable pail liners, the diaper genie "diaper sausages," the extra fuel for trucks to ship diapers to the stores, etc. I think you get the picture.