Where can I find a good piano teacher in Perth?

At school:

Learning to play piano at school is a common way students can access regular piano lessons and many schools have a dedicated music department. Ask if your child's school provides piano lessons or can recommend a piano teacher.

Private Piano Teachers: 

Hiring a private piano teacher is the most common way of accessing lessons in person and this can often be done at the teacher's premises or in your own home, depending on which teacher you decide on.

I recommend using the piano teacher finder at the West Australia Music Teacher's Association website for finding a teacher close to you.

I also recommend joining the Facebook Group "Perth Piano Players" and asking in there for a local teacher recommendation