A Manual Siphon Will You Need One to Survive? Actually, you need at least two if not three manual siphons. One for drinking water only, one for fuels and possibly one for chemicals, such as liquid bleach that needs to be moved from one container to another when pouring is not a good option, for example.
A hand pump is essential if you have stored water in a large container that does not have a large enough opening in which to dip water. Furthermore, dipping water out could contaminate the water source, whereas you can sanitize the siphon for drinking water only rather easily each time to prevent contamination of the source.
A manual siphon only requires a small opening, which also lessens the chance of contamination. Some of the larger water barrels may not have a lid that can be removed. They may only have a cap for filling and extraction. Removing the entire lid greatly increases the chances of contaminants getting into your drinking water source.
You, of course, never want to use a siphon for drinking water that was ever used (even once) to siphon any fuels or chemicals regardless of how well you think you may have cleaned it.
What can you do with a hand siphon? You can siphon gas from a gas can without a spout into a vehicle, or in some cases siphon gas from a vehicle into a gas can or another vehicle. If the grid fails gas pumps will not work, but yet there will be many vehicles, and underground fuel storage tanks, but you must have a way of extracting that fuel for your use.
A hand siphon is ideal for filling up lanterns and kerosene heaters as well. Fill directly from the fuel container and there is no need for a funnel. If you have a five-gallon can of kerosene and heater that needs to be filled you cannot simply tip the can up and pour in the tiny hole and even with a funnel you would end up spilling precious fuel, not to mention creating a fire hazard in some cases. A hand siphon that you pump gets the job done without any spills, without handling heavy cans and helps prevent hazardous spills.
To help filter water from a contaminated water source you can use a ranger band to secure several layers of cheesecloth to the end that is inserted into the contaminated source. This filtering technique will only filter out large debris, so additional filtering to trap micro-contaminates will be required before boiling or chemical treatment for purification.
Use your siphon to remove water and/or antifreeze from disabled vehicles to add to a vehicle that operates. Again, during a crisis, normal supply chains will not be operational, and so if you need water or coolant for your radiator, you need a method to extract from one vehicle to another.
There are drain valves, of course, to drain radiators but they may be inoperable or otherwise cannot be reached to allow for draining, not to mention you would need a receptacle that would fit under the drain to collect the fluid.
There are other uses obviously, and you are only limited by your imagination, so start thinking of other ways you can use a manual siphon during a crisis, or in any survival situation, and remember, you need one dedicated to potable water only.