Your toilet is a hardy ceramic fixture that can last for decades. But unlike, say, a bathtub, your toilet also has several moving parts inside of it that can cause problems if they become unbalanced. Toilet malfunctions can result if the toilet attempts to flush with too much or too little water. Here are some of the reasons why this could occur.
Poorly designed or DIY low flow
Some of the earliest low-flow toilet designs were, understandably, less sophisticated than later models. This meant that the early low-flow designs didn't always flush adequately with the small amount of water they were using. In effect, they didn't have enough water for a good flush. If your toilet is one of these, this could be why you're struggling with weak flushes.
A related reason for a weak flush is if the toilet has had a DIY remodel to force it to flush with less water. Although eco-conscious goals are admirable, placing 2-liter bottles of water in your toilet's tank could potentially weaken the flush by reducing the amount of water available in the tank.
Even if your toilet has the right amount of water in the tank, that water needs to quickly rush down into the toilet bowl when you flush, or the flush might not be effective. If your toilet's flush chain is incorrectly adjusted, this could keep the water from all getting to the bowl for a quick, powerful flush.
Try shortening the chain a link or two and then see if this helps increase the speed and power of the flush.
Old toilet tank
While a poorly designed or DIY low-flow toilet may use too little water for a powerful flush, the opposite can be true with an even older model. Older toilet tanks use several gallons of water per flush. If yours is doing this, it may seem to work fine, yet may be costing you money.
If you have an older toilet from before 1992, it may use 3.6 gallons per flush. You can switch to a (modern, well-designed) low-flow model and save 2.32 gallons on each flush. If you flush five times per day, that's about 348 gallons per month for each member of your family, which could definitely save you money over time.
Uncalibrated fill valve
If your toilet doesn't have an adjustable fill valve, the fill valve likely fills the bowl and tank at the same time during the flush recovery period. The bowl likely fills first, then loses quite a bit of water down the overflow since the fill valve keeps going until the tank is full.
Choosing a fill valve that can be adjusted to fill the bowl slightly slower may help you save an additional gallon or more per flush.
As you can see, toilet flush issues aren't always simple. If your toilet continues to use flush with the wrong amount of water a residential plumbing
service can help you get to the bottom of a wasteful or insufficient toilet flush and get everything working efficiently again.