Interesting note: you can probably call your bank up and request that the disallow ACH withdrawals from your account if triggered by some third party.

You can still get ACH deposits. You can still use the bank's bill pay and they will send the payments over ACH (so you can push funds over ACH from the account). But someone else can't _pull_ funds over ACH from that account.

Certainly the banks I use have this as an option, and it's useful sometimes. As long as you remember and don't try to pull yourself from one of your other accounts, of course.