It's hard trying to describe the whole water/pipe thing here. There's nothing wrong with ours, it just gets a little bubbly sometimes. In the first picture you can see the bubbles coming up out of the drain in the floor (there's a floor drain in both bathrooms here). Then I got in the shower and a ton more came out. It seems to be bubblier when you use a new bar of soap.
I explained how the rain water drains into our tank, and that's the water we use. But we also have what they call 'gray water'. The water from the sinks and drains (not the toilets obviously) get recycled and that waters our yard. That sounds like a really good idea, but we live on over an acre-- and the sprinkler system (using the gray water) is only in one area. We just need to buy some more hoses and then we'll have a greener yard.
Jason's cousin who lives down the road recently ran out of water. I went to visit her and she kicked her tank-- and it was definitely dry. She had to call a water truck to come fill it up. It cost her $100. So it's nice if it rains-- you get nice clean FREE water, but if you use it up it just sucks.