Can I use Unity Pro water in the free version now?

I have the unity pro water prefab in my scene and it works fine but when I build my game the water just shows up pink? I made sure I included the shader. So is it because I use the free version? Because I thought they made all pro assets usable in Unity free?

Yes you can use it (provided it’s Unity 5 and up).

Generally materials which are pink suggest that either there’s a shader error, missing texture or that your GPU doesn’t support a feature that the shader is using.

Yes, you can. The only difference between pro/plus and free is dark skin, splash and services which allow for better working in bigger teams.

I believe you should import water from unity 5 standard assets. Shader language changes quite often and breaks older shaders if they are too advanced.