#An example of the untainting code for a value not being deleted:
if (param('house') =~ /^([\dA-Za-z '-]{1,20})$/ ) {
	$house = $1;
    } else {
	push @problem, "House name or number";
        push @delete, "house";
    }

#And one that is:
if (param('email1') =~ /^(([\w\.]{1,40})@([\w\.]{1,30}))$/ ) {
	    $email = $1;
	} else {
	    push @problem, "e-mail address";
	    push @delete, "email1";
	}
#I'm aware that this will disallow some valid e-mail addresses, but I'm  not worrying about that for the moment

#And the code that should delete all the invalid input:
my $i;
	foreach $i (@delete) {
	    $query->delete($i);
	}