I had aphid problems early this year. Luckily, I left them alone and they were either eaten or left. What you can do is try to attract beneficial insects such as ladybugs, or buy them from a garden store.

Sometimes the treatment is worse than the pest. ;) But there are tons of discussions here on aphids and how to control them that a search will pull up for you. Here on links to 3 good ones full of info.

Desperate for an aphid cure

Organic way to get rid of aphids

How do you kill aphids?

Personally, if the water blast doesn't last then I use 1 T of liquid soap mixed in 1 gal. of water and spray the aphids rather than drench the plants. Works for me. ;)

Hope this helps.

Dave