Also,  in an existing building seperating grey and blackwater would be prohibitively costly at best. 

So its Black water , you dont have different pipes for grey and black , they all go to the septic tank .  

Greek Islands and especially Cyprus one will notice every building has a black water tank on top of the roof.. this gives all the hot water one would need.. that would be a nice step forward for desert areas of US.. not that expensive and totally basic.. just a black tank.. on the roof.. gravity floor water in black tank is very warm/hot. 

Toilet water is "black" water and must be mitigated to remove any sewage.

Here's how the septic system works: Water used goes out to the septic tank (Kitchen, laundry, toilets, shower, bath, sink), solids remain at the bottom of the tank and then black water goes out to the Drainfield.To keep a healthy drainfield, I recommend servicing the septic tank every 3-5 years, if it's a SFH, and,  1 to 2 years if its multi family. 

I do have 2" memory foam pads and a Serta Black water proof padded cover over the whole shebang. 

Was it grey water (generally clean water) or was it black water (sewage)?

I own a PM company in US and have never even heard of FirstService Residential and never in the conversation of the "nationwide aspirants" that every hedge fund and VC group seems to be swooning over.So, perhaps it is the child of Blackwater or some other MegaBuying entity that handles the management?

Obviously the size of the park has a bearing on reserves needed as does factors such as the park situation for the black water disposal, city or septic.

So, Lubbock or Amarillo might be more like what I'm accustomed to.If you ever swing by Blackwater Coffee Co., I'll buy you a cup of their excellent piñon coffee!