Quantitative Aptitude is a key component of most competitive exams, and one of the most practical chapters is Pipe and Cistern. This topic is a variation of Time and Work, focused on fluid-based problems like filling or emptying tanks using inlets and outlets. In this blog, we have provided all the details about Pipe and Cistern concepts, types of questions asked, time-saving tricks, strategies, and more.
Download Pipe and Cistern Questions PDF
Pipes and Cisterns is an important topic in the Quantitative Aptitude section of various competitive exams, including SSC, Railways, Banking, and other government exams. Practicing frequently asked Pipes and Cistern questions can help candidates improve their calculation speed, understand common question patterns, and increase accuracy in the exam. Below is a set of Pipes and Cistern practice questions, Candidates can practice these questions and download the PDF for preparation.
Practice Pipe and Cistern Questions Live
Pipes and Cistern questions are frequently asked in SSC and other competitive examinations. Most questions are based on concepts such as inlet pipes, outlet pipes, filling and emptying tanks, combined efficiency, leakages, and pipes working together. Below is a collection of Pipes and Cistern questions for live practice.
1. Pipes A and B can fill a tank in 20 minutes and 30 minutes respectively. If both are opened together, in how much time will the tank be filled?
2. Pipes A and B can fill a tank in 15 minutes and 25 minutes respectively. If both are opened together, in how much time will the tank be filled?
3. Pipes A, B and C can fill a tank in 15 minutes, 20 minutes and 30 minutes respectively. If all three are opened together, how long will they take to fill the tank?
4. Pipes A, B and C can fill a tank in 12 minutes, 18 minutes and 36 minutes respectively. If all three are opened together, how long will they take to fill the tank?
5. Pipes A and B can fill a tank in 25 minutes and 30 minutes respectively. If both are opened together, in how much time will the tank be filled?
6. Pipes A and B can fill a tank in 6 hours and 8 hours respectively. If both are opened together, in how much time will the tank be filled?
7. Pipes A and B can fill a tank in 10 hours and 15 hours respectively. If both are opened together, in how much time will the tank be filled?
8. Pipes A, B and C can fill a tank in 12 hours, 20 hours and 30 hours respectively. If all three are opened together, how long will they take to fill the tank?
9. Pipes A and B can fill a tank in 14 hours and 21 hours respectively. If both are opened together, in how much time will the tank be filled?
10. Pipes A, B and C can fill a tank in 16 hours, 24 hours and 48 hours respectively. If all three are opened together, how long will they take to fill the tank?
11. Pipes A and B can fill a tank in 10 hours and 15 hours respectively, while pipe C can empty it in 30 hours. If all three are opened together, in how much time will the tank be filled?
12. Pipes A and B can fill a tank in 12 hours and 18 hours respectively, while pipe C can empty it in 36 hours. If all three are opened together, in how much time will the tank be filled?
13. Pipes A and B can fill a tank in 8 hours and 12 hours respectively, while pipe C can empty it in 24 hours. If all three are opened together, in how much time will the tank be filled?
14. Pipes A and B can fill a tank in 6 hours and 8 hours respectively, while pipe C can empty it in 24 hours. If all three are opened together, in how much time will the tank be filled?
15. An inlet pipe can fill a tank in 20 minutes, while an outlet pipe can empty the full tank in 30 minutes. If both are opened together when the tank is empty, in how much time will it be filled?
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What is Pipe and Cistern in Quantitative Aptitude?
Pipe and Cistern questions deal with the rate of flow of liquid in or out of a tank. Pipes can fill (inlets) or empty (outlets) a tank, and the problem revolves around how long it takes to fill or empty the cistern. This topic checks:
- Basic time-work concept
- Logical application of speed-flow analogy
- Efficiency understanding of combined work (inlets vs outlets)
Why is Pipe and Cistern Important in Competitive Exams?
Pipe and Cistern is one of the easier chapters that, if prepared well, can help you score full marks in the exam from this topic
| Exam | No. of Questions | Difficulty |
| SSC CGL / SSC CHSL | 1-2 | Easy |
| IBPS PO / SBI PO | 1-2 | Moderate |
| RRB NTPC / RRB Group D | 1 | Easy |
| State PSC / Police | 1-2 | Moderate |
Terms Used in Pipe and Cistern Questions
Terms commonly used in pipe and cistern types of questions are as follows:
| Term | Details |
| Inlet Pipe | A pipe that fills the tank |
| Outlet Pipe | A pipe that empties the tank |
| Net Work | Total work done when both inlet and outlet operate together |
| Efficiency (Rate) | Part of the tank filled/emptied in 1 hour or 1 minute |
| LCM Method | Used to avoid fractional calculations (consider tank as 60L, 120L) |
| Negative Work | Outlet pipe’s work is taken as negative in combined equations |
Concepts of Pipe and Cistern Questions
Some of the common concepts used while solving pipe and cistern questions are as follows:
| Concept | Explanation |
| Inlet fills in ‘x’ hr | 1/x part of tank is filled per hour |
| Outlet empties in ‘y’ hr | 1/y part is emptied per hour (taken as -1/y in equations) |
| Net Rate Formula | Net rate = (Inlet rate – Outlet rate) |
| Time to Fill/Empty | Time = Work ÷ Net Rate |
| If both pipes open together | Total time = 1 / (1/x – 1/y) or 1 / (1/x + 1/y), depending on in/outlet |
| Partial Fill Problem | Use ratio method or unitary method for “half-filled” scenarios |
What Are the Types of Pipe and Cistern Questions in Quantitative Aptitude?
Types of questions commonly asked from the topic are as follows:
- Direct Questions: One inlet or outlet with simple time calculation
- Combined Pipes: Both pipes operate together (positive and negative work)
- Leakage-based: Leakage reduces flow; subtract leakage rate from inlet
- Variable Pipes: Pipes open/close after certain time
- Cyclic Pattern: Pipes open in fixed order repeatedly
Pipe and Cistern Formulas
Here are the time-saving formulas and logical templates:
- If a pipe fills a tank in x hours, its rate = 1/x
- If a pipe empties a tank in y hours, its rate = –1/y
- If both pipes work together, net rate = (1/x – 1/y) or (1/x + 1/y)
- If the tank is partially filled/emptied, apply the formula: Time=VolumeNet Rate\text{Time} = \frac{\text{Volume}}{\text{Net Rate}}Time=Net RateVolume
- LCM shortcut: Assume tank volume = LCM of individual times to simplify
Pipe and Cistern Tricks for SSC CGL and Other Exams
Some of the quick time saving tricks are as follows:
- Assume Tank Capacity as LCM of all time values (e.g., 60L, 120L)
- Treat outlet as negative work when working with both inlet and outlet
- Skip unit conversion unless time is in minutes and rate is per hour
- Use ratio method for partial fill questions
- Cross-check units (minutes/hour) before applying formulas
- Reverse solve from options if stuck with calculations
FAQs
They are based on time and work, involving pipes filling or emptying a tank.
Divide 1 by the time it takes to fill or empty the tank.
Treat outlet work as negative when calculating combined rate.
Net rate = 1/x ± 1/y, depending on inlet or outlet involvement.
It involves subtracting the leak’s rate from the inlet pipe’s rate.
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