In the Preferences menu of the game, there are various toggles for the types of content you want to enable or disable. One of those is "Pissing" so depending on your content choices you make in the Preferences screen, the game may or may not feature watersports related content now or in the future.

(As an example, I played through with all male content disabled and only Lesbian content enabled, and as of release v0.2.1.5 there was no watersports content that I encountered during my playthrough. It may be solely tied to existing male content, or planned for a future update but not included yet on the lesbian-enabled paths. Or perhaps I simply missed it by choosing incorrectly at a given scene.)

Not the primary focus, and this is a very large game with a wide variety of content, but there are toilet peeping scenes and characters that are interested in watersports play.

While not the primary focus of the game, there are a few scenes with some very nice urination related content if you choose to pursue it.

Not the main focus, but Grandma's House includes some watersports content

The protagonist in Harmony Girls takes an interest in pee play. There are some related story scenes and repeatable events, but it's not the main focus of the game's content.

Not the main focus, but Hex includes some watersports content

Not the main focus, but Succubus Stories includes some watersports content

Not the main focus, but Lust Age includes some watersports content

Not the main focus, but Messy Academy includes some watersports content

Not the main focus, but Harem Hotel includes some watersports content

Not the main focus, but Kana Sensei includes some watersports content

Not the main focus, but Naughty Lyanna includes some watersports content

Not the main focus, but Naughty Lyanna includes some watersports content