In some instances, watery semen may be a normal occurrence. For instance, pre-ejaculate is often clear and watery. Some studies indicate that a man's diet may also effect the consistency of his semen, and frequent ejaculation can also result in watery semen. Men with low sperm counts may also have semen that is thinner than normal.
Semen consists of a few components. Sperm makes up only a small percentage of semen, and it is produced in the testicles. Roughly half of semen is made up of a fluid produced in the seminal vesicles. This fluid is very high in fructose, which provides energy for the sperm to swim. The prostate and bulbourethral glands also produce fluids that make up the rest of the sperm.
A substance known as pre-ejaculate is produced by the bulbourethral glands, or Cowper's glands prior to ejaculation. This fluid is used for lubrication during sexual intercourse and ejaculation, and it can often be seen on the tip of a man's penis when he is sexually aroused. Although this substance alone does not contain sperm and is not actually semen, it can resemble watery semen.
Diet may also affect, among other things, the consistency of semen. A man may have watery semen if he does not get the proper amount of certain essential nutrients. Protein, for instance, is believed to help make semen thicker. A man who does not get enough protein in his diet may have watery semen.
The consistency of semen is also often affected by how often a man ejaculates. Generally, sperm takes a few months to mature in the testicles. If a man ejaculates several times each day, such as with frequent masturbation or intercourse, his testicles will usually not be able to produce enough sperm to keep up. This will often result in less sperm present in the semen. Instead of the semen being thick and white, the lack of sperm could cause watery semen.
A low sperm count could also possibly cause watery semen in some men, due to the same reason: not enough sperm in the semen. Several factors can affect a man's sperm count. If the testicles are kept at too high of a temperature, for instance, sperm might not develop properly. Clothing that is too tight can sometimes cause a rise in the temperature of a man's testicles, especially if he exercises with this clothing on.