# Water Pressure, small inlet vs. large outlet

• FriscoGary
In summary, the conversation discusses a sewer box with a 2' x 2' x 2' size and an 8" drainage inlet pipe and an 18" drainage outlet pipe. The question is whether the incoming water from a 2' x 2' grate opening at the top will cause backflow into the 8" inlet pipe as water is also discharging out the 18" outlet pipe. The answer depends on the pressures and elevations at the far ends of the pipes, but in theory, there could be some backup into the inlet.
FriscoGary
If there is a "sewer box" (2' x 2' x 2') with a 8" drainage inlet pipe into it and it has a 18" drainage outlet pipe to
discharge water entering into the sewer box and the large 2' x 2' grate opening at the top...IF the entire sewer box is inundated with storm water, will the incoming water thru the top 2' x 2' grate allow water into (backflow) the 8" inlet pipe as water is also discharging out the 18" drainage outlet pipe? I would think the storm water entering from the grate opening would mainly discharge out the larger 18" discharge pipe and sort negate or
"push back" any water trying to drain into the box from the small 8" pipe. My question is will the volume of water from the top grate not allow any water from the small 8" inlet to enter into this system if it is inundated from the top. My thought was all the pressure from the top would negate or equalize any from the 8" pipe...any insight would help!

The diameter of the inlet and outlet are less important than the pressures or elevations at the far ends.

In theory, pressure in the middle could cause flow in both directions, backing up the inlet, but whether this happens or not depends on more details than the sizes.

The elevations are equal for the 8" inlet and 18" outlet and their far ends are lower than the top of the "sewer box" grate inlet. The 8" inlet only has
pressure from the water draining into it and it is a level pipe.

FriscoGary said:
The elevations are equal for the 8" inlet and 18" outlet and their far ends are lower than the top of the "sewer box" grate inlet. The 8" inlet only has
pressure from the water draining into it and it is a level pipe.

In that case, yes you will get some backup into the inlet.

## What is water pressure?

Water pressure is the force exerted by water on a surface, usually measured in pounds per square inch (psi). It is a measurement of how much force is needed to push water through a system.

## How does water pressure differ between small inlets and large outlets?

The size of the inlet and outlet can affect water pressure because a smaller inlet means that the same amount of water has to pass through a smaller space, increasing the pressure. On the other hand, a larger outlet allows water to flow more freely, leading to lower pressure.

## Can water pressure be controlled by adjusting the size of the inlet and outlet?

Yes, the size of the inlet and outlet can be adjusted to control water pressure. By increasing the size of the inlet, more water can enter the system, resulting in a decrease in pressure. Similarly, decreasing the size of the outlet can increase pressure as the same amount of water has to pass through a smaller space.

## What are the effects of high water pressure?

High water pressure can lead to increased stress on pipes, fixtures, and appliances, potentially causing them to leak or break. It can also result in higher water bills and wasted water. In extreme cases, it can even cause damage to a home's plumbing system.

## How can water pressure be measured and monitored?

Water pressure can be measured using a pressure gauge, which is typically attached to a faucet or water line. To monitor water pressure, it is recommended to regularly check the pressure gauge and keep track of any changes. If there are significant fluctuations in pressure, it may be necessary to adjust the size of the inlet and outlet or call a professional for further analysis.

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