Water pressure is simply $pgh/2$ for a vertical wall parallel to the depth of the water at exactly the half the water's depth. Suppose the wall is tapered (angled) slightly at around 2 degrees from the y-axis (parallel to the wall). How would you measure the pressure at this point? Would it be the contributing pressure from both the vertical and horizontal pressure? As such: $pgh
\sin (\theta) + 1/2pgh\cos(\theta)$.

I'm assuming pressures can be summed as forces. This may be false.