It's good that your asking this, a lot of kids just throw their stuff in the washing machine with regular detergent and then they wonder why their jacket isn't too waterproof or breathable anymore. Regular powder detergents block the pores on your jacket, which causes the waterproofing and breathability of the fabric to deteriorate. It's important to choose a detergent designed for your tech shells, personally I use Nikwax Tech Wash for my outer shells, because I find it works best. It's designed to maintain and revitalize the DWR (Durable Water Repellency) Coating on your outerwear, which can wear away over time. From time to time I also use Nikwax TX Direct Wash In, this adds DWR. Its important to note that if you're going to use TX Direct Wash In, do so after washing the garment(s) with Tech Wash first.
You should be able to find these out most outdoor shops near you, if not the local ski shop. But I've also attach links to the products on Nikwax's website, so you can see what you're looking for.
My UK/EURO BST Thread - http://www.newschoolers.com/ns/cult/forumthread/thread_id/743385/
Check my blog for updates and reviews: http://aslansskiblog.blogspot.co.uk/
Joey -Formerly *III.JVD.III*
I post from mobile the majority of the time, so if the above is incomprehensible, I apologize.