Heh yes we've all been there! I remember when I was constructing my own backpack system, me and matt exchanged a good few ideas.
Speaking from my own experience, there wasn't a system available that fit my needs at the time (a backpack), so I built one myself. Now, however, there are systems that you can buy that are cheaper and more pro-looking than my constructed one, and if I was doing it now I'd just buy one.
The problem as I see it, is that there are a number of "systems" for sale which are, lets face it, cobbled together bits of 'junk' that nobody should ever buy, like that one I put the picture of above. The only reason people actually do buy them is because there is sometimes a lack of knowledge amongst window cleaners.
Having said that, there are some great little residential systems around, and one of them is the Omnitrolley. The only problem is that 50 litres is a bit on the heavy side to be lifting in and out of the van, but of course you don't have to fill it right up.
Water consumption is a tricky area, and most manufacturers take the view that you need about 1.5 litres a minute flowing through the brush. In my humble opinion, the jets that I have seen fitted to brushes let FAR to much water through (usually in thin squirts). The best way (as explained to me by Jeff Brimble) is to use spray jets that allow a really good flow of water over the glass, but only use abou 0.75 litres per minute. When I have lent my modified poles out to other people, they can't believe how good they are and how much less water is needed.
Doing this greatly reduces the size of the system you need, and I believe that for 1 person for 1 day, 150 litres is more than enough. If you can put something together yourself and make it look pro, then more power to you! its a good way to start off, and eventually when you're ready to buy a manufactured system you'll have a much better idea of what you need.
A word of caustion though, I recently met a window cleaner who had installed a 400 litre tank into his van, up against the bulkhead. Now the bulkhead had dented inward in the shape of the tank, and that was just from the normal braking action. I dread to think what would happen in the case of a shunt. My advice in this area, and I genuinely mean this with window cleaners interests at heart, is if you are going to install a tank yourself, put it into a trailer, rather than in the back of your van. Its only a matter of time before somebody is squashed to death or badly injured by this type of accident, and even after all the debate and contraversy, the manufacturers (even otherwise reputable ones) are just not taking this seriously. I have seen some installations by well regarded manufacturers that have practically no integrity at all, and would break free even from a 10mph shunt.
All in all, I think that everyday window cleaners are fast waking up to the benefits of water fed pole, and thats a really great thing. It doesn't cost that much to get a system of some kind, and really, with the increased speed of working, there's no reason not to in my opinion!
-Philip
