Ok, you need to get started on treating the cats.
Once the cats are being treated, the fleas will die off never to return,but it could take a few months.
Frontline on its own won't wash - it just kills the adults, and all the time they'll be laying new eggs before dying so once you have an infestation of this level you need frontline combi or ideally program. I say this as I didn't bother to treat my cat for several months, and finally realised it was a problem when we were getting bitten - I started off with frontline from petmeds, it didn't work, then a few months later started combi (it stops eggs hatching apparently) also useless here, then began Program (infertilises the fleas directly) and carried on with the frontline too and it's worked.
I combed her the other night and not one flea, we haven't eben bitten for a few months either, so gradually it all comes together because anything hatching from the floor etc will jump onto her and be zonked. Eggs can live on the floor up to a year.
There is a safe spray from the vets, you could do your floors with that but it's not cheap - around 20 quid I think, and pointless if you don't treat the cats. If they stay on program (or frontline once problem is under control, properly) any they pick up from elsewhere will die quickly.
HTH, don't worry - they prefer cat blood and can't live on humans, despite giving it a try!!