At Euro RSCG, Waters worked on the "artery" anti-smoking campaign for the British Heart Foundation.
In her new role, she will build PAA's planning credentials and develop strategy for all clients.
The appointment marks a return to the direct marketing agency for Waters. She was the planning director in 2001 in addition to her role as a senior planner at Partners BDDH, which baked the agency's launch in 1998.
PAA, which was taken over by Snyder, the parent of Arnold and Brann Worldwide, was acquired by Havas in 2000 and merged with Euro RSCG Wnek Gosper last year. PAA became independent from Havas in July this year.
Phil Andrews, PAA's managing partner, said: "Kate is a great thinker, she encourages the best possible creative ideas to emerge and she is excellent at new business.
"It's fantastic news for the agency that she is returning and fulfils a key plank of building our board post-buy-out from Havas.
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