## Core Concept
The purification of water involves various processes to remove contaminants and make water safe for drinking. These processes can include physical methods like filtration and sedimentation, chemical methods like chlorination and coagulation, and biological methods. The goal is to remove pathogens, chemicals, and other contaminants.

## Why the Correct Answer is Right
The correct answer, which is not specified here, needs to be evaluated based on the options provided for A, B, C, and D. Generally, in water purification, methods like boiling, chlorination, and filtration are known to be effective. For instance, chlorination is widely used for its ability to kill bacteria and other microbes. However, without the specific details of each option, we focus on the general principles that make a statement about water purification true or false.

## Why Each Wrong Option is Incorrect
- **Option A:** Without specifics, we can't directly address why A is incorrect, but typically, statements about water purification being unnecessary for boiled water or that filtration removes all contaminants could be incorrect.
- **Option B:** Similarly, without details, if B suggests that water purification is only needed for surface water and not groundwater, this could be seen as incorrect because both can have contaminants.
- **Option C:** If C mentions that all purification methods remove chemicals and pathogens equally, this could be incorrect because different methods have different efficacies against various contaminants.
- **Option D:** If D states something universally acknowledged as true about water purification (like the use of chlorine for disinfection), then it would not be the incorrect statement.

## Clinical Pearl / High-Yield Fact
A key point to remember is that **boiling** is a universally effective method for purifying water, capable of killing all forms of microbial life. This method is particularly recommended in areas where access to chemically purified or filtered water is not available.

## Correct Answer: D.