Have a Bissell Little Green cleaning machine at my office for cleaning up spills. Well someone used it and never emptied the dirty water from the tank. I know it is going to stink to high heaven when I turn it on. Is there a way to clean it or would I be best just chucking it in the trash and buy a new one?

I threw mine away and bought a new one. Worked like a charm, smelled like it was brand new.

Empty it and try running some vinegar water through it, best of luck

I rinsed mine out with a high pressure hose then ran warm water and vinegar through the vac and attachments. Let it sit for a day, rinse, repeat and it's been fine ever since. Just make sure the filters are cleaned or replaced.

Vinegar-and you can buy a higher concentrate for cleaning use...maybe at HD

Clean it out as best as you can, then bleach and water, let that sit in the tank for a few hours.

Try TSP or it’s environmentally friendly substitute?

After it’s cleaned and if you have access to (or rent one) an Ozone Machine should further help.

Quite often an Ozone Machine works wonders.