Higher capacity water tanks

I'm wondering if anyone has found larger clean and dirty water tanks for the t10 and t20 omnis, I have seen plumbing kits but wife has said no. Currently i can do the house with daily washing for the mop pads, but I prefer the deep clean one, with the daily version it can do entire house and put itself up clean on one tank, but the deep clean one it needs two tank changes. I'm wondering if anyone has found XL Size tanks, or am i gonna have to semi babysit deep clean cycles.