After seeing someone recommend it on baby bumps, I bought this one: King Size SafeRest Premium Hypoallergenic Waterproof Mattress Protector - Vinyl Free https://www.amazon.com/dp/B003PWK2A8/ref=cm_sw_r_cp_apa_6lOgybV6Z17F3 It's been working great. Less than $40, No sound, feels soft, keeps sheets from pulling off bed and had good reviews.
We bought a pack of these and I put one down under the sheet on my side of the bed. I figure that it would probably catch the worst of it if my water was to break. I also have one down on the couch and in my car just in case.