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Tank Volume

Environmental Engineering · FE Reference Handbook section

Environmental Engineering
9 formulas
10 exam-style examples
~60 min
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Handbook notes for this section

Definitions and conditions exactly as the handbook states them.

  • FSi can be neglected if primary sludge is not included on the sludge flow to the digester.
  • VOLATILE SOLIDS REDUCTION IN AN AEROBIC DIGESTER AS A FUNCTION
  • OF DIGESTER LIQUID TEMPERATURE AND DIGESTER SLUDGE AGE

Core formulas for this FE topic

Definitions, applicability, units, assumptions and worked examples for each relation.

Worked exam-style examples

The four ways this section is written on the real exam — thoughts first, then equations, then substitution.

Example 1
Tank Volume — solve for tank volume — Tank Volume

tank volume required for a target detention time in a storage tank Given flow rate (Q) = 17,300 m^3/day; hydraulic detention time (theta) = 15.2500 day, determine the tank volume (V) in m^3.

Given

  • flowrate(Q)=17,300m3/dayflow rate (Q) = 17,300 m^3/day
  • hydraulicdetentiontime(theta)=15.2500dayhydraulic detention time (theta) = 15.2500 day

Find

tank volume (V), in m^3

Start with the thinking

  • The governing relation printed in this handbook section is Tank Volume.
  • Everything except V is given, so isolate V symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Tank volume for a treatment basin is the product of flow rate and required hydraulic detention time.
V = tank volume

Figure 1 — schematic for Tank Volume — solve for tank volume — Tank Volume

Step-by-step solution

  1. Step 1 — State the governing relation:

    V=Q×θV = Q \times \theta
  2. Step 2 — Rearrange symbolically for V:

    V=Q θV = Q\,\theta
  3. Step 3 — List the givens: flow rate (Q) = 17,300 m^3/day, hydraulic detention time (theta) = 15.2500 day.

  4. Step 4 — Substitute the given values:

    V=17300 15.2500V = 17300\,15.2500
  5. Step 5 — Evaluate:

    V = 263825\ \text{m^3}
  6. Step 6 — Check: returning V = 263,825 m^3 to

    V=Q×θV = Q \times \theta

    reproduces the given quantities, and both sides carry the same units.

Answer:
V = 263825\ \text{m^3}

Why the other options are there

  • 527,650 — kept a factor of two that cancels in the correct rearrangement.
  • 131,913 — dropped that same factor in the other direction.
  • 290,208 — rounded an intermediate value before the final step.

Reference: FE Handbook — Tank Volume

Example 2
Tank Volume — solve for flow rate — Tank Volume (2)

tank volume sizing for an equalization basin Given hydraulic detention time (theta) = 3.8000 day; tank volume (V) = 184,669 m^3, determine the flow rate (Q) in m^3/day.

Given

  • hydraulicdetentiontime(theta)=3.8000dayhydraulic detention time (theta) = 3.8000 day
  • tankvolume(V)=184,669m3tank volume (V) = 184,669 m^3

Find

flow rate (Q), in m^3/day

Start with the thinking

  • The governing relation printed in this handbook section is Tank Volume.
  • Everything except Q is given, so isolate Q symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Tank volume for a treatment basin is the product of flow rate and required hydraulic detention time.
V = tank volume

Figure 2 — schematic for Tank Volume — solve for flow rate — Tank Volume (2)

Step-by-step solution

  1. Step 1 — State the governing relation:

    V=Q×θV = Q \times \theta
  2. Step 2 — Rearrange symbolically for Q:

    Q=VθQ = \dfrac{V}{\theta}
  3. Step 3 — List the givens: hydraulic detention time (theta) = 3.8000 day, tank volume (V) = 184,669 m^3.

  4. Step 4 — Substitute the given values:

    Q=1846693.8000Q = \dfrac{184669}{3.8000}
  5. Step 5 — Evaluate:

    Q = 48597\ \text{m^3/day}
  6. Step 6 — Check: returning Q = 48,597 m^3/day to

    V=Q×θV = Q \times \theta

    reproduces the given quantities, and both sides carry the same units.

Answer:
Q = 48597\ \text{m^3/day}

Why the other options are there

  • 97,194 — kept a factor of two that cancels in the correct rearrangement.
  • 24,299 — dropped that same factor in the other direction.
  • 53,457 — rounded an intermediate value before the final step.

Reference: FE Handbook — Tank Volume

Example 3
Tank Volume — solve for hydraulic detention time — Tank Volume (3)

detention tank volume calculated from plant flow rate Given flow rate (Q) = 17,990 m^3/day; tank volume (V) = 245,191 m^3, determine the hydraulic detention time (theta) in day.

Given

  • flowrate(Q)=17,990m3/dayflow rate (Q) = 17,990 m^3/day
  • tankvolume(V)=245,191m3tank volume (V) = 245,191 m^3

Find

hydraulic detention time (theta), in day

Start with the thinking

  • The governing relation printed in this handbook section is Tank Volume.
  • Everything except theta is given, so isolate theta symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Tank volume for a treatment basin is the product of flow rate and required hydraulic detention time.
V = tank volume

Figure 3 — schematic for Tank Volume — solve for hydraulic detention time — Tank Volume (3)

Step-by-step solution

  1. Step 1 — State the governing relation:

    V=Q×θV = Q \times \theta
  2. Step 2 — Rearrange symbolically for theta:

    θ=VQ\theta = \dfrac{V}{Q}
  3. Step 3

    Listthegivens:flowrate(Q)=17,990m3/day,tankvolume(V)=245,191m3List the givens: flow rate (Q) = 17,990 m^3/day, tank volume (V) = 245,191 m^3
  4. Step 4 — Substitute the given values:

    θ=24519117990\theta = \dfrac{245191}{17990}
  5. Step 5 — Evaluate:

    θ=13.6293 day\theta = 13.6293\ \text{day}
  6. Step 6 — Check: returning theta = 13.6293 day to

    V=Q×θV = Q \times \theta

    reproduces the given quantities, and both sides carry the same units.

Answer:
θ=13.6293 day\theta = 13.6293\ \text{day}

Why the other options are there

  • 27.2586 — kept a factor of two that cancels in the correct rearrangement.
  • 6.8146 — dropped that same factor in the other direction.
  • 14.9922 — rounded an intermediate value before the final step.

Reference: FE Handbook — Tank Volume

Example 4
Tank Volume — solve for tank volume (case 2) — Tank Volume (4)

tank volume required for a target detention time in a storage tank Given flow rate (Q) = 12,900 m^3/day; hydraulic detention time (theta) = 0.5500 day, determine the tank volume (V) in m^3.

Given

  • flowrate(Q)=12,900m3/dayflow rate (Q) = 12,900 m^3/day
  • hydraulicdetentiontime(theta)=0.5500dayhydraulic detention time (theta) = 0.5500 day

Find

tank volume (V), in m^3

Start with the thinking

  • The governing relation printed in this handbook section is Tank Volume.
  • Everything except V is given, so isolate V symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Tank volume for a treatment basin is the product of flow rate and required hydraulic detention time.
V = tank volume

Figure 4 — schematic for Tank Volume — solve for tank volume (case 2) — Tank Volume (4)

Step-by-step solution

  1. Step 1 — State the governing relation:

    V=Q×θV = Q \times \theta
  2. Step 2 — Rearrange symbolically for V:

    V=Q θV = Q\,\theta
  3. Step 3 — List the givens: flow rate (Q) = 12,900 m^3/day, hydraulic detention time (theta) = 0.5500 day.

  4. Step 4 — Substitute the given values:

    V=12900 0.5500V = 12900\,0.5500
  5. Step 5 — Evaluate:

    V = 7095\ \text{m^3}
  6. Step 6 — Check: returning V = 7,095 m^3 to

    V=Q×θV = Q \times \theta

    reproduces the given quantities, and both sides carry the same units.

Answer:
V = 7095\ \text{m^3}

Why the other options are there

  • 14,190 — kept a factor of two that cancels in the correct rearrangement.
  • 3,548 — dropped that same factor in the other direction.
  • 7,805 — rounded an intermediate value before the final step.

Reference: FE Handbook — Tank Volume

Example 5
Tank Volume — solve for flow rate (case 2) — Tank Volume (5)

tank volume sizing for an equalization basin Given hydraulic detention time (theta) = 3.2500 day; tank volume (V) = 40,693 m^3, determine the flow rate (Q) in m^3/day.

Given

  • hydraulicdetentiontime(theta)=3.2500dayhydraulic detention time (theta) = 3.2500 day
  • tankvolume(V)=40,693m3tank volume (V) = 40,693 m^3

Find

flow rate (Q), in m^3/day

Start with the thinking

  • The governing relation printed in this handbook section is Tank Volume.
  • Everything except Q is given, so isolate Q symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Tank volume for a treatment basin is the product of flow rate and required hydraulic detention time.
V = tank volume

Figure 5 — schematic for Tank Volume — solve for flow rate (case 2) — Tank Volume (5)

Step-by-step solution

  1. Step 1 — State the governing relation:

    V=Q×θV = Q \times \theta
  2. Step 2 — Rearrange symbolically for Q:

    Q=VθQ = \dfrac{V}{\theta}
  3. Step 3 — List the givens: hydraulic detention time (theta) = 3.2500 day, tank volume (V) = 40,693 m^3.

  4. Step 4 — Substitute the given values:

    Q=406933.2500Q = \dfrac{40693}{3.2500}
  5. Step 5 — Evaluate:

    Q = 12521\ \text{m^3/day}
  6. Step 6 — Check: returning Q = 12,521 m^3/day to

    V=Q×θV = Q \times \theta

    reproduces the given quantities, and both sides carry the same units.

Answer:
Q = 12521\ \text{m^3/day}

Why the other options are there

  • 25,042 — kept a factor of two that cancels in the correct rearrangement.
  • 6,260 — dropped that same factor in the other direction.
  • 13,773 — rounded an intermediate value before the final step.

Reference: FE Handbook — Tank Volume

Example 6
Tank Volume — solve for hydraulic detention time (case 2) — Tank Volume (6)

detention tank volume calculated from plant flow rate Given flow rate (Q) = 14,580 m^3/day; tank volume (V) = 192,478 m^3, determine the hydraulic detention time (theta) in day.

Given

  • flowrate(Q)=14,580m3/dayflow rate (Q) = 14,580 m^3/day
  • tankvolume(V)=192,478m3tank volume (V) = 192,478 m^3

Find

hydraulic detention time (theta), in day

Start with the thinking

  • The governing relation printed in this handbook section is Tank Volume.
  • Everything except theta is given, so isolate theta symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Tank volume for a treatment basin is the product of flow rate and required hydraulic detention time.
V = tank volume

Figure 6 — schematic for Tank Volume — solve for hydraulic detention time (case 2) — Tank Volume (6)

Step-by-step solution

  1. Step 1 — State the governing relation:

    V=Q×θV = Q \times \theta
  2. Step 2 — Rearrange symbolically for theta:

    θ=VQ\theta = \dfrac{V}{Q}
  3. Step 3

    Listthegivens:flowrate(Q)=14,580m3/day,tankvolume(V)=192,478m3List the givens: flow rate (Q) = 14,580 m^3/day, tank volume (V) = 192,478 m^3
  4. Step 4 — Substitute the given values:

    θ=19247814580\theta = \dfrac{192478}{14580}
  5. Step 5 — Evaluate:

    θ=13.2015 day\theta = 13.2015\ \text{day}
  6. Step 6 — Check: returning theta = 13.2015 day to

    V=Q×θV = Q \times \theta

    reproduces the given quantities, and both sides carry the same units.

Answer:
θ=13.2015 day\theta = 13.2015\ \text{day}

Why the other options are there

  • 26.4030 — kept a factor of two that cancels in the correct rearrangement.
  • 6.6008 — dropped that same factor in the other direction.
  • 14.5217 — rounded an intermediate value before the final step.

Reference: FE Handbook — Tank Volume

Example 7
Tank Volume — solve for tank volume (case 3) — Tank Volume (7)

tank volume required for a target detention time in a storage tank Given flow rate (Q) = 13,270 m^3/day; hydraulic detention time (theta) = 3.4000 day, determine the tank volume (V) in m^3.

Given

  • flowrate(Q)=13,270m3/dayflow rate (Q) = 13,270 m^3/day
  • hydraulicdetentiontime(theta)=3.4000dayhydraulic detention time (theta) = 3.4000 day

Find

tank volume (V), in m^3

Start with the thinking

  • The governing relation printed in this handbook section is Tank Volume.
  • Everything except V is given, so isolate V symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Tank volume for a treatment basin is the product of flow rate and required hydraulic detention time.
V = tank volume

Figure 7 — schematic for Tank Volume — solve for tank volume (case 3) — Tank Volume (7)

Step-by-step solution

  1. Step 1 — State the governing relation:

    V=Q×θV = Q \times \theta
  2. Step 2 — Rearrange symbolically for V:

    V=Q θV = Q\,\theta
  3. Step 3 — List the givens: flow rate (Q) = 13,270 m^3/day, hydraulic detention time (theta) = 3.4000 day.

  4. Step 4 — Substitute the given values:

    V=13270 3.4000V = 13270\,3.4000
  5. Step 5 — Evaluate:

    V = 45118\ \text{m^3}
  6. Step 6 — Check: returning V = 45,118 m^3 to

    V=Q×θV = Q \times \theta

    reproduces the given quantities, and both sides carry the same units.

Answer:
V = 45118\ \text{m^3}

Why the other options are there

  • 90,236 — kept a factor of two that cancels in the correct rearrangement.
  • 22,559 — dropped that same factor in the other direction.
  • 49,630 — rounded an intermediate value before the final step.

Reference: FE Handbook — Tank Volume

Example 8
Tank Volume — solve for flow rate (case 3) — Tank Volume (8)

tank volume sizing for an equalization basin Given hydraulic detention time (theta) = 0.7000 day; tank volume (V) = 185,687 m^3, determine the flow rate (Q) in m^3/day.

Given

  • hydraulicdetentiontime(theta)=0.7000dayhydraulic detention time (theta) = 0.7000 day
  • tankvolume(V)=185,687m3tank volume (V) = 185,687 m^3

Find

flow rate (Q), in m^3/day

Start with the thinking

  • The governing relation printed in this handbook section is Tank Volume.
  • Everything except Q is given, so isolate Q symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Tank volume for a treatment basin is the product of flow rate and required hydraulic detention time.
V = tank volume

Figure 8 — schematic for Tank Volume — solve for flow rate (case 3) — Tank Volume (8)

Step-by-step solution

  1. Step 1 — State the governing relation:

    V=Q×θV = Q \times \theta
  2. Step 2 — Rearrange symbolically for Q:

    Q=VθQ = \dfrac{V}{\theta}
  3. Step 3 — List the givens: hydraulic detention time (theta) = 0.7000 day, tank volume (V) = 185,687 m^3.

  4. Step 4 — Substitute the given values:

    Q=1856870.7000Q = \dfrac{185687}{0.7000}
  5. Step 5 — Evaluate:

    Q = 265267\ \text{m^3/day}
  6. Step 6 — Check: returning Q = 265,267 m^3/day to

    V=Q×θV = Q \times \theta

    reproduces the given quantities, and both sides carry the same units.

Answer:
Q = 265267\ \text{m^3/day}

Why the other options are there

  • 530,534 — kept a factor of two that cancels in the correct rearrangement.
  • 132,634 — dropped that same factor in the other direction.
  • 291,794 — rounded an intermediate value before the final step.

Reference: FE Handbook — Tank Volume

Example 9
Tank Volume — solve for hydraulic detention time (case 3) — Tank Volume (9)

detention tank volume calculated from plant flow rate Given flow rate (Q) = 9,670 m^3/day; tank volume (V) = 354,469 m^3, determine the hydraulic detention time (theta) in day.

Given

  • flowrate(Q)=9,670m3/dayflow rate (Q) = 9,670 m^3/day
  • tankvolume(V)=354,469m3tank volume (V) = 354,469 m^3

Find

hydraulic detention time (theta), in day

Start with the thinking

  • The governing relation printed in this handbook section is Tank Volume.
  • Everything except theta is given, so isolate theta symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Tank volume for a treatment basin is the product of flow rate and required hydraulic detention time.
V = tank volume

Figure 9 — schematic for Tank Volume — solve for hydraulic detention time (case 3) — Tank Volume (9)

Step-by-step solution

  1. Step 1 — State the governing relation:

    V=Q×θV = Q \times \theta
  2. Step 2 — Rearrange symbolically for theta:

    θ=VQ\theta = \dfrac{V}{Q}
  3. Step 3

    Listthegivens:flowrate(Q)=9,670m3/day,tankvolume(V)=354,469m3List the givens: flow rate (Q) = 9,670 m^3/day, tank volume (V) = 354,469 m^3
  4. Step 4 — Substitute the given values:

    θ=3544699670\theta = \dfrac{354469}{9670}
  5. Step 5 — Evaluate:

    θ=36.6566 day\theta = 36.6566\ \text{day}
  6. Step 6 — Check: returning theta = 36.6566 day to

    V=Q×θV = Q \times \theta

    reproduces the given quantities, and both sides carry the same units.

Answer:
θ=36.6566 day\theta = 36.6566\ \text{day}

Why the other options are there

  • 73.3131 — kept a factor of two that cancels in the correct rearrangement.
  • 18.3283 — dropped that same factor in the other direction.
  • 40.3222 — rounded an intermediate value before the final step.

Reference: FE Handbook — Tank Volume

Example 10
Tank Volume — solve for tank volume (case 4) — Tank Volume (10)

tank volume required for a target detention time in a storage tank Given flow rate (Q) = 19,130 m^3/day; hydraulic detention time (theta) = 14.2500 day, determine the tank volume (V) in m^3.

Given

  • flowrate(Q)=19,130m3/dayflow rate (Q) = 19,130 m^3/day
  • hydraulicdetentiontime(theta)=14.2500dayhydraulic detention time (theta) = 14.2500 day

Find

tank volume (V), in m^3

Start with the thinking

  • The governing relation printed in this handbook section is Tank Volume.
  • Everything except V is given, so isolate V symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Tank volume for a treatment basin is the product of flow rate and required hydraulic detention time.
V = tank volume

Figure 10 — schematic for Tank Volume — solve for tank volume (case 4) — Tank Volume (10)

Step-by-step solution

  1. Step 1 — State the governing relation:

    V=Q×θV = Q \times \theta
  2. Step 2 — Rearrange symbolically for V:

    V=Q θV = Q\,\theta
  3. Step 3 — List the givens: flow rate (Q) = 19,130 m^3/day, hydraulic detention time (theta) = 14.2500 day.

  4. Step 4 — Substitute the given values:

    V=19130 14.2500V = 19130\,14.2500
  5. Step 5 — Evaluate:

    V = 272603\ \text{m^3}
  6. Step 6 — Check: returning V = 272,603 m^3 to

    V=Q×θV = Q \times \theta

    reproduces the given quantities, and both sides carry the same units.

Answer:
V = 272603\ \text{m^3}

Why the other options are there

  • 545,205 — kept a factor of two that cancels in the correct rearrangement.
  • 136,301 — dropped that same factor in the other direction.
  • 299,863 — rounded an intermediate value before the final step.

Reference: FE Handbook — Tank Volume

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