When choosing an appropriate material for a water pump case, pump makers take a variety of things into consideration to evaluate all effects and aspects. The selection process is frequently a compromise between price, availability, and performance. In most cases, the most cost-effective material will also be the best material for a given application. Cast iron is an excellent example of something that can have superior corrosion resistance to other, more expensive materials when it comes into contact with certain liquids, and it also has the added benefit of having noise reduction capabilities. Plastics and other non-metallic materials are one more example of inexpensive materials that nonetheless possess unique features such as resistance to wear and a high strength-to-weight ratio. When cost is not a factor, plastics are frequently the material of choice. If the end user finds themselves in a position where they must choose between two different hardware options, they should not automatically believe that the alternative with the higher price is superior or more advantageous. The following are some of the criteria that play a role in the selection of the material:
- The type of pump
- Pump components
- Pumping fluid (temperature, wear, corrosion, erosion)
- Techniques employed in production (casting or machining)
- Initial cost
- Economic life
- Material characteristics (strength, strength limit, compression tightness, gravity properties, etc.)
- Safe storage of dangerous goods
From one manufacturer to the next, the final selection of pump materials that are made available for the same working conditions may be different. One of the reasons for this is that manufacturers frequently choose to specialize in particular production processes (such as injection molding, casting, welding, machining, and so on), and the material that is used will be optimally suited to the particular kind of fabrication that is used. When it comes to material selection, large pumps require a different approach than smaller pumps. For instance, pumps that are used to handle sludge, gravel, and coal are frequently chosen according to the smallest volume of particles that they are able to carry. Because of their size and the requirement that they endure both wear and impact, these pumps typically have rubber linings or are made of wear-resistant hardened cast iron. In addition, when annual pump requirements of a particular volume are modest, the pump volume uniformity should be reduced so as to accommodate big differences in the necessary performance. This is done so as to handle large changes in required performance. Because of this, there are restrictions placed on the kinds of materials and the scope of the available options for these pumps. When it comes to pumps used in power plants and utilities, such as water supply and sewage, ferrous metals are frequently employed. Under these circumstances, the same restrictions apply. Materials chosen for use in wet areas need to be resistant to all naturally occurring water types, including chlorinated water, in order to be suitable for use in small household pumps such as pressure units for the home, pumps for swimming pools and gardens, multistage cavitation pumps, and the like. 
Because of the high volume of pumps that are sold for such applications, tens of thousands of components may be required each year. As a result, injection molded plastics are commonly used, and a wide variety of materials that have excellent properties of strength and resistance to wear are available. In addition to small residential pumps and large industrial pumps, there is a comprehensive selection of medium-sized pumps that are suited for a variety of applications. This typical pump range can be broken down into the following three categories:
- Special purpose pumps (e.g., marine, food and beverage pumps)
- Chemical pumps
- Water pumps that can be used for various purposes
When it comes to pumps designed for specific applications, the manufacturer will pick and match components made of materials that are well-known for their resistance to the pumped liquid. When it comes to packing, chemical pumps should be designed to be made using a variety of materials and designs because it is possible that they may need to handle a specific liquid that contains many chemicals. The choice of material for water pumps designed for general use is not as straightforward as it might appear at first glance. 
These pumps are subjected to dissolved salts, gases, pollutants, and other corrosive elements, which frequently result in unexpectedly severe corrosion issues. May be exposed to these elements. In order to circumvent such challenges, it is necessary to investigate available hardware solutions. Cast iron bodies, high tensile steel shafts, cast iron or bronze impellers, and worn parts are common components found in low and medium-pressure water pumps that are designed for general-purpose use. The use of stainless steel in the construction of these pumps is becoming increasingly common. In these designs, the impellers, diffusers, and casings are all made out of stainless steel that has been pressed and welded. Some producers create these products using a casing made of cast iron and an impeller made of stainless steel. Stainless steel of grade 304 or 316 is typically used for applications that take place in water. However, grade 316L is typically utilized for applications that are more abrasive. This is done to prevent corrosion at grade limits in heat-affected parts of the weld. For high-pressure applications, the casing is often made of ductile iron, cast iron, forged or welded steel, and it also typically has high-alloy steel shafts, bronze or stainless-steel impellers, and stainless-steel distributors. 
The pump technical document contains a broad material guide diagram for the liquid pH range.
- All stainless-steel pumps: The components of the pump that come into direct contact with the fluid being pumped are constructed of a steel that is resistant to corrosion and has qualities that are appropriate for the intended usage.
- These pumps can now be replaced by a group of pumps constructed of non-metallic materials. However, the replacement will depend on the flow and pressure requirements.
- All Bronze Pumps: Every element that comes into contact with the fluid being pumped is made of a bronze formula that has properties that are appropriate for the task at hand.
- Bronze pumps have every component that comes into contact with the fluid being pumped made of bronze.
- Cast iron is used for the pump body, impeller, impeller rings, and brushes (if fitted) in bronze-mounted pumps. These pumps also have bronze shaft bags (if fitted).
- When referring to bronze pumps, the phrase "zinc-free bronze" is frequently used. This specification was created because of the difficulties associated with the removal of corrosion while working with brass and modified brass.
- To illustrate, what we require is a substance that does not corrode. The element is bronze. There is no need to eliminate cracking if the zinc content is up to 15%.
- All iron pumps have components made of ferrous metals, as do all other components that come into direct contact with the liquid being pumped.
- Pumps that have a stainless-steel coupling have a housing that is made of a material that is appropriate for the task at hand, while the impeller, impeller rings, brushes, and shaft housing (if fitted) are made of corrosion-resistant steel that has properties that are appropriate for the task at hand.