diff --git a/src/water_cmd.cpp b/src/water_cmd.cpp
--- a/src/water_cmd.cpp
+++ b/src/water_cmd.cpp
@@ -136,11 +136,14 @@ CommandCost CmdBuildShipDepot(DoCommandF
 		Depot *depot = new Depot(tile);
 		depot->build_date = _date;
 
-		if (wc1 == WATER_CLASS_CANAL || wc2 == WATER_CLASS_CANAL) {
-			/* Update infrastructure counts after the unconditional clear earlier. */
-			Company::Get(_current_company)->infrastructure.water += wc1 == WATER_CLASS_CANAL && wc2 == WATER_CLASS_CANAL ? 2 : 1;
-		}
-		Company::Get(_current_company)->infrastructure.water += 2 * LOCK_DEPOT_TILE_FACTOR;
+		uint new_water_infra = 2 * LOCK_DEPOT_TILE_FACTOR;
+		/* Update infrastructure counts after the tile clears earlier.
+		 * Clearing object tiles may result in water tiles which are already accounted for in the water infrastructure total.
+		 * See: MakeWaterKeepingClass() */
+		if (wc1 == WATER_CLASS_CANAL && !(HasTileWaterClass(tile) && GetWaterClass(tile) == WATER_CLASS_CANAL && IsTileOwner(tile, _current_company))) new_water_infra++;
+		if (wc2 == WATER_CLASS_CANAL && !(HasTileWaterClass(tile2) && GetWaterClass(tile2) == WATER_CLASS_CANAL && IsTileOwner(tile2, _current_company))) new_water_infra++;
+
+		Company::Get(_current_company)->infrastructure.water += new_water_infra;
 		DirtyCompanyInfrastructureWindows(_current_company);
 
 		MakeShipDepot(tile,  _current_company, depot->index, DEPOT_PART_NORTH, axis, wc1);