There are several types of water gates that may be placed.
Water gate new 2m under decorating in the construction menu; category: decorating; cost: $100
Water gate new 4m; daily maintenance: $0; category: decoration; cost: $200
Daily maintenance: water gate old 2m, $0
Price: $100; Category: Decoration
Daily maintenance: water gate old 4m, $0
Type: Decoration; Cost: $200
Maintenance cost per day: $0 Manhole round
Price: $350; Category: Decoration
Maintenance cost per day: $0 Manhole square
Price: $350; Category: Decoration
Daily maintenance: $0
Water gate new 2m TipCollision under silos in the construction menu; Category: Grain silos; Cost: $100
Water gate new 4m, daily maintenance: $0 TipCollision: $200; Category: Grain silos
Daily maintenance: water gate old 2m, $0 Category: Grain silos; TipCollision; Cost: $100
Daily maintenance: $0 Water gate old 4m TipCollision Type: Grain silos Cost: $200 Daily maintenance: $0 These versions may be positioned at the end of the silage silos to prevent the chopped material from being forced out.
In order to tip bulk items in hallways without TipCollision, the chutes may also be positioned in the walls of the corridors.

Thanks to Achi_Wastl