I am not sure how many gallons we get on a recharge of ours. We do go one week between charges while we are in the RGV, which has VERY hard water. We do NOT have a washer/dryer, but, do have the 3 yorks and my hair is long (takes more water to rinse it clean, than when it is short).
Ours came with some gauge to tell you when you need to recharge. Cept, it did not work. I think (slippery memory from the soft water, sorry, that was pathetic, eh??
) that it did not work cause there was never enough water pressure to make the little gauge move. Al pitched it. We just recharge once a week.
BTW, he uses a bit of Rustout in each charge. Well, I think that is what it is called. (Maybe that slippery memory comment was right on, eh???)