Hidden under all the shade cloth ate 2 x 1000 lt tanks They look like this Looking at it overall :- The metal frame holds a plastic poly tank which is not always UV proof hence being wrapped in shade cloth the frame is open able so you can replace the tank if needed. you cann ot stand on the plastic tank but the frame is OK. At the top:- there is a large red screw cap fitted cap fitted so you can easly see in and pressure clean it if required. Inside the cap is a smaller cap 40mm that a pvc pipe can go straight in and its a good tight fit. as you cam see I have one of your diverter taps fitted to direct the water to one or the other 2000l water total. At the bottom:- Is a shultz valve and cap, you need to buy an adapter to get from the corporate thread to a standard garden hose thread. I swap the outlet hose between the two and the is off to a pressure pump seen on the L/H tank near the trolley.
