The Ideal PH for azaleas is 5.0 - 5.5.

Organic matter added to the soil can modify the soil PH.

The mulch you use can effect the soil PH. Excellent acidic mulches for azaleas are pine needles, pine straw shavings, and pine bark mulch.

Azaleas are sensitive to irrigation water with undesirable alkalinity, and 7.0 is definitely going to make them unhappy, no matter what other measures you take.

Talk to your local AG Extension office about what you may be able to add to the water that will create the ideal PH. Remember that it is best to water infrequently, deeply, and slowly, rather than frequently and shallowly.

Good luck!

Hi AGAIN
CANCEL THE 'PINE BARK MULCH' PART OF MY LAST REPLY.
I DISCOVERED THAT BARK WILL PULL NITROGEN OUT OF THE SOIL, ESPECIALLY IF IT IS WORKED INTO THE SOIL WITHOUT DECOMPOSING, SO IF YOU HAVE ANY, PUT IT INTO THE COMPOST PILE.
I DON'T CARE FOR ANY OF THE BARK MULCHES, BECAUSE THEY TEND TO FLOAT AWAY WHEN IT RAINS.