The answer to 'septic tank foul smell' is that a foul odor from your septic tank is usually caused by a problem with the system. Common causes include a full or clogged septic tank, a broken drain field, or issues with the plumbing. Symptoms may include a strong rotten egg smell, sewage backup, or standing water around the septic tank or drain field.
In many cases, the solution is to have the septic tank pumped and inspected by a professional plumber. This can help clear any clogs or buildup and ensure the system is functioning properly. If the issue is with the drain field, more extensive repairs or replacement may be needed. It's generally best to call in a professional plumber to diagnose and address septic tank problems, as improper DIY attempts can make the issue worse.