Worksheet Grade 9 Math

Brindlemoor Pressure Zones: Elevation and PSI Worksheet

A grade 9 worksheet on the fictional Brindlemoor Water District, converting ground elevation to water pressure in psi across three streets with the 0.433 rule.

Grade: Grade 9
Subject: Math
Material: Worksheet
Time: 40 min
Prep: No prep
Materials: Calculator

Standards

HSA-CED.A.1 Common Core Math

Create equations and inequalities in one variable and use them to solve problems. Include equations arising from linear and quadratic functions, and simple rational and exponential functions.

How this material aligns: Items 6 and 7 have students write and solve the one-variable equation P = 0.433 times (660 minus E) for a target pressure or elevation.

All materials for HSA-CED.A.1 →

HSN-Q.A.1 Common Core Math

Use units as a way to understand problems and to guide the solution of multi-step problems; choose and interpret units consistently in formulas; choose and interpret the scale and the origin in graphs and data displays.

How this material aligns: Every item carries the units psi per foot and feet per psi through the elevation-to-pressure conversion, the dimensional discipline this standard requires.

All materials for HSN-Q.A.1 →

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This material is in the public domain (CC0) and may be copied, edited, and shared freely, without attribution. Updated 2026-07-23.

Objectives

Students will convert feet of water height above a point into pressure in psi.
Students will write and solve a one-variable equation for pressure at a given elevation.
Students will compare pressure-zone results against minimum and comfort service standards.

Vocabulary

Pressure zone: A pressure zone is a section of a water system that a utility manages separately because it sits at a different elevation than the rest of the town. Utilities create pressure zones so that water pressure stays safe and steady for everyone, whether they live at the bottom of a hill or near the top.

Also: head, elevation, psi, booster pump

Teacher overview

The fictional Brindlemoor Water District pumps water into one tall tank, then serves homes at three different ground elevations. All three streets are in one pressure zone because they share one tank's water surface; the booster pump in item 8 creates a separate, higher zone for Summit Lane. Pressure at any home depends only on the height of water standing above that home. This worksheet has students turn elevation into pressure with the operator rule that each foot of water height adds 0.433 psi, then work the rule backward to find the elevation that meets a pressure target.

Brindlemoor Pressure Zones: Elevation and PSI Worksheet — Grade 9 Math

Name: ____________________________ Date: ______________

Student Worksheet

Brindlemoor (a fictional water district) holds its tank water surface at an elevation of 660 feet above sea level. Use these facts for every item:

Head is the feet of water above a point: head = 660 minus the ground elevation.
Pressure in psi = head in feet times 0.433.
Feet of water above a point = pressure in psi times 2.31.
Most states require at least 20 psi throughout the system. Utilities aim for 40 to 80 psi at the tap.

River Road sits at a ground elevation of 480 feet. Find the head, in feet of water, above River Road.
Find the water pressure at River Road. Round to the nearest whole psi.
Birch Street sits at 540 feet. Find the head and the pressure at Birch Street. Round to the nearest whole psi.
Summit Lane sits at 600 feet. Find the pressure at Summit Lane. Round to the nearest whole psi.
Does Summit Lane meet the 20 psi minimum, and by about how many psi does it clear or miss it?
Write an equation for the pressure P at a home with ground elevation E, given the tank surface at 660 feet. Then use it to find the pressure at a home at 510 feet. Round to the nearest whole psi.
A new hydrant must have at least 40 psi. Solve for the highest ground elevation that still gives 40 psi. Round to the nearest foot.
A booster pump raises the effective water surface for Summit Lane to 700 feet. Find the new pressure at Summit Lane (elevation 600 feet). Round to the nearest whole psi.
A home gauge reads 61 psi. Find the feet of water standing above that gauge. Round to the nearest foot.
Explain why homes at lower elevations get higher pressure than homes at higher elevations, even though all three streets share one tank.

From Water for Schools (waterforschools.org). This material is in the public domain (CC0) and may be copied, edited, and shared freely.

Answer Key

Answer: 180 ft. Head = 660 minus 480 = 180 feet of water above River Road.
Answer: 78 psi. 180 ft times 0.433 = 77.94, which rounds to 78 psi.
Answer: 52 psi. Head = 660 minus 540 = 120 ft; 120 times 0.433 = 51.96, about 52 psi.
Answer: 26 psi. Head = 660 minus 600 = 60 ft; 60 times 0.433 = 25.98, about 26 psi.
Answer: Yes, by about 6 psi. Summit Lane is near 26 psi; 25.98 minus 20 = 5.98, roughly a 6 psi margin.
Answer: 65 psi. The equation is P = 0.433 times (660 minus E). At E = 510: P = 0.433 times 150 = 64.95, about 65 psi.
Answer: 568 ft. Solve 40 = 0.433 times (660 minus E). Then 660 minus E = 40 divided by 0.433 = 92.38 ft, so E = 660 minus 92.38 = 567.62, about 568 feet.
Answer: 43 psi. New head = 700 minus 600 = 100 ft; 100 times 0.433 = 43.3, about 43 psi.
Answer: 141 ft. 61 psi times 2.31 = 140.91, about 141 feet of water above the gauge.
Answer: Lower homes have more feet of water standing above them, so their head is larger. Because pressure equals head times 0.433, a larger head gives a higher pressure at the same tank.

Differentiation

Support

Give students a printed strip with two labeled arrow rules, "feet to psi: multiply by 0.433" and "psi to feet: multiply by 2.31," and one worked example that uses numbers not on this worksheet. Provide the head values for items 1 through 4 already subtracted so students can focus on the multiplication.

Extension

Ask students to write a single equation for the pressure at any elevation E and graph P against E for elevations from 480 to 660 feet. Then have them read the graph to find the elevation where pressure drops to exactly 30 psi and confirm it algebraically.

ELL supports

Pre-teach "elevation," "head," "pressure," and "booster pump" with a labeled side-view sketch of a tank on a hill feeding three houses at different heights. Provide a sentence frame for item 10: "Lower homes have more ___ above them, so they have ___ pressure."