pg_dump password

Hey,

We want to close up the db so people can't alter the database, so we
thought of using
a password. The problem now is that we can't have pg_dump run because it
prompts
for a password.

Are there any alternatives for closing up the database? Having host/user
based trust
isn't really an option because it's a web application, and if the web
user can simply
access the database, it would be all to easy to install a web pg admin
package.

If not, is there a way to pass on a password to the pg_dump(all) utility?

regards,
Q Beukes