Toilet models that use the Sloan Flushmate System will sometimes make a moaning or groaning noise when flushed. Other times they continuously gurgle, like the sound of water leaking or bubbling. The groaning noise occurs just AFTER the toilet has flushed, while the tank is refilling. The gurgling noise is continuous. A somewhat loud whooshing noise is normal when this type of toilet is flushed, this sounds similar to the noise a commercial toilet makes. Here's how to fix it.