How Do I Know If I’ve Put Too Much Water in My Bong?
You can decide by these points. Is there resistance? When there is too much water in a bong, there is a high resistance, or drag, when inhaling, similar to sucking in thick syrup through a straw, as the smoke path prolongs and friction is greater against the larger water volume.
Is there a grunting sound?
The classic indicator of too much water translates to large gurgling or burping sounds —unlike the clean and crisp bubbling of proper levels — that result from giant bubbles bursting against extra water resistance. Bubbles — visually huge and chaotic, smoke churning with violent force instead of dispersing evenly and indicating over-agitation that denudes taste of its Subtleties. It also suppresses the aroma of terpenes; I’ve personally experienced inhaling smoke that tastes bland and tasteless.

Is there any splashing?
Splashback offers the clearest warning: water shoots into the mouthpiece, wetting lips, tongue, or mouth through intense suction even as the surface sits perilously close to the stem’s exit. Tilting the bong exacerbates this, sending water up in powerful draws, causing the sessions to turn messy and unpleasant. In extreme cases, vigorous bubbling sends droplets into the bowl and soaks the flower before combustion, wasting some, as wet herb won’t burn evenly over time.
How Much Should I Submerge the Downstem in Water?
I think the downstem is supposed to be submerged in water (1/4 – 1/2) inch (about 0.6-1.3 cm) below its opening or holes. For any downstem with no diffuser I just always add water until the bottom opening is under water, so that the diffusion is enough while reducing splashback.

Naturally, there’s a tip for use: After inserting the downstem into the glass water bong, add water, so that at least the holes at the bottom of the downstem are totally submerged (most standard glass weed bongs submerge them for about 1-2 inches (approximately 2.5-5 cm)). But here, the length of the downstem determines how much water must be used because if it is short and doesn’t extend to the bottom of the smoke chamber, you should use less water. One way to achieve this is to set the bong to your typical smoking angle and observe the angle at which the downstem lies relative to the water. In the tilted smoking posture (which many smokers adopt as a shortcut strategy, resulting in an enhanced experience), the downstem can be naturally submerged more deeply.
Does changing the water level make hits smoother or stronger?
With an appropriate water level and stable bubbling, the smoke in the water stays at a lower temperature longer because the heat gradually dissipates through diffusion across the water surface. In my own experience, cooler smoke is much smoother than hot smoke, which leads to the greatest reduction of throat and lung irritation for a longer, more pleasant session—though lower resistance yields richer flavors at the cost of some smoothness. This trade-off affords water level corrections to customize inhalation based on preferences.

Of course, you can slightly increase the water level to increase controllable draw resistance, although this will sacrifice some impact, but I think it’s worth it because it results in better cooling and particulate filtration, thus achieving larger, gentler inhales. often resulting in greater overall cannabinoid use, even in light… airflow.
How Often Should I Change Bong Water?

Following my habit, I change the water after every one cigarette or after every 2-3 bowls of smoke to retain its freshest taste and consistency. Heavy smokers will frequently recommend switching water between every bowl, with a new bong producing noticeably smoother hits and better flavor than one filled with resin and plant material. If you smoke several times daily, the minimum number of changes you make should be to water, at least once daily, but more can be changed between sessions, as much as possible. The logic is that stale bong water develops bacteria and biofilm — protective material bacteria form on surfaces — and they build up in hours, turning the water cloudy and unpleasant and possibly affecting your health. Frequency, though, varies based on your usage pattern; light users who smoke once daily can sustain water for up to 2-3 days if it is cleaned regularly, while heavy smokers who smoke 20+ times daily are required to change water multiple times per session.