BuildCraft version: 7.99.14
Forge version: 14.23.1.2601
Link to crash report or log: https://pastebin.com/YcdcaFfW
Singleplayer or multiplayer: Multiplayer
Additional information: Crash has happened twice in the past couple of days and has required restoring a backup. Nothing changed in other mods since several days before the first crash. Seems both were caused by a pump but can't work out why. Think both pumps were being used for water. Thanks!

Unfortunately I seem to had forgotten that I can't just print out a fluid stack as-is... although seeing as that's a buildcraft tank class I can still take a look at it.