I should say, I don't see a downside to getting some dew collectors going however you like to play. Dukes are easy to come by (haven't had a game where I had a shortage of Dukes - heck, we were melting them down for brass) and I wouldn't consider it a waste to set a few of these up. You'll always find enough for yourself by looting, but if there's more of you it can be more of a strain to rely on looted water, and you also need to consider those sudden times you will need industrial-quantities of water for a lot of recipes all at once.
First time I played A21 with a buddy, we went a little overboard -- three groups of eight dew collectors in non-POI fields around the town. We used to have them in the base ... but then the Pimps added the heat factor and the screamer situation was out of control. Currently I got by with three, but pushed it to six and then nine because the filters were the best reward on offer.