Grey tank and black empty at pretty much the same rate on our vintage. Must be something to newer models. There is always a drip if level at dump time when camping at water and electric hookup only. Hope you get this problem solved!
__________________
1975 Sovereign
"The Silver Bullet"
2013 F350 Super Duty 6.7 Liter Diesel
WBCCI #8578
This website is not affiliated with or endorsed by the Airstream, Inc. or any of its affiliates. Airstream is a registered trademark of Airstream Inc. All rights reserved. Airstream trademark used under license to Social Knowledge LLC.