The first solution is obvious prevention. Your best bet to avoid the use of chemicals is to prevent clogs. Invest in fixtures on your sinks and showers to catch debris before it makes its way down the drain. This can prevent his clogs especially. However some things cannot be caught like soap scum, oils and grease. There are limited ways to prevent these materials from building up (though buildup takes much longer). In that case, look into enzyme cleaners like Bio Clean. Bio Clean uses bacteria and enzymes to break down organic materials. Homemade drain cleaners can be useful as well. A mix includes vinegar, baking soda, and boiling water can clear out blocks. If none of the less abrasive techniques work, it is time to call a plumber. Calling a plumber ensures the job is done correctly, and doesnt balloon into a plumbing emergency.