Clay Water Buckets don't work with Pam's HarvestCraft recipes.

Examples: An iron bucket on the crafting table equals 4 fresh water buckets. A fresh water bucket (or an iron bucket of water) and a pot equals HC salt.

Clay water buckets should provide the same, especially considering the limitations on iron from using IguanaTiC.

Might be as simple as registering the clay water bucket as listAllwater oredict.