If you have ever gone to by a new tent, you can see that in almost every tent indicates the water column from the ground cloth and canvas. But what does it mean exactly, a water column of 3000, 5000 or even 10 000 mm? A water column says something about the amount of water that can be a tent ground sheet or "enduring" before water penetrates through it. The value is expressed in mmWS (Millimeter Wassersaüle). A water column of 3000 mm basically means that a cloth has only water flow when there is a pressure arises which is similar to the weight of a column of water three meters in height. How does it work? The water column indicates how many mm of water per cm 2 on the cloth can stand before the material is leaked. Specifically: a tent, a ground sheet or waterproof clothing is a (transparent) column put that slowly filled with water. As more water enters the column, the pressure on the lower layer becomes greater. Eventually the pressure will go through the material through leaks. The higher the water column, the longer it takes for the material from leaking. When waterproof? Material is called waterproof at a water column of 800 mm. In general it can be stated that a tent fabric with a water column of 2000 mm is also kept at a long-lasting waterproof rain. However, it is even safer to choose a minimum of 3000 mm water column. In a groundsheet water column is at higher value. A ground cloth is deemed reliable only waterproof with a water column of 5000 mm. However, there are also ground sheet with a water column of 10000 mm or higher. This higher value is easy to explain. On a groundsheet is sat or slept, so there is a lot of pressure on a regular basis. A tent will endure less direct powers. It is also wise to protect your groundsheet by using a separate ground sheet or tent diaper. Canvas type The concept of water column applies only to tent cloths which are made of nylon or polyester and have a water-resistant coating, usually a PU coating. It does not apply to cotton tents or tents with a combination of cotton / polyester (Technical Cotton / TC). Namely cotton threads are impregnated and swell up when it rains. As a result, cotton cloth is waterproof but also breathable. A tent cloth of nylon or polyester, although it is waterproof, but has no breathability because the coating completely shut-off the fabric. Of course there is in cotton tents indeed say something about the water column of the groundsheet because, like polyester or nylon tents using plastic land sailing (mostly polyester or polyethylene), a cotton ground cloth is theoretically possible, but would never be strong enough to serve as a reliable foundation for campers. Following is test of canvas. The tents were followed for 6 months (equivalent to 4 days of use for about a month to 3.5 years) were exposed to wind and weather in which the water-tightness at the beginning and the end of the period, was measured. The results: Terra Nova Solar Minor: from 700mm to 7000mm + TNF Mountain Marathon: 7000 + mm to 700mm Marmot Home Alone: 700mm to 7000mm + MSR Microzoid: 700mm to 7000mm + MH PCT1: 7000mm to 2100mm + Vango Phantom150: 7000mm to 2100mm + Hillberg Akto: 7000mm to 2800mm + Macpac Microlight: remained at 7000mm + Lightwave ZR0 Trek remained 7000mm + Recommended best family tent with high water column 1.Outwell Vision 200 - Pop-up Tent - 2-Person - Green Item Description • Additional information: - Fiberglas (6 mm) - Flame-retardant - Compact pack size - Good ventilation - For Mount the inner tent • Scope of supply: With carrying bag Material • Outer tent: 100% polyester • Water column outer tent: 3000 mm to 10 000 mm • Inner tent: 100% polyester • awning Ground 100% polyethylene • Water column tent floor: 3000 to 10000 mm • Poles: fiberglass 2. High Peak Levanto 2 - Pop-up Tent - 2-Person - Purple The High Peak pop-up tent Levanto 2 for 2 people is a high throw tent with taped seams so that there are no leaks come at the seams. The outer tent is waterproof to 3000 mm which is the perfect protection against heavy rain. This spacious tent with wide entrance is ideal in construction and very quick setup and has extra ventilation. The patented design with two arcs provides additional space. There's mosquito net at the entrance holding some insects out and also provides extra ventilation. Also, there are multiple storage bags available on the inside. This tent has a small pack size which makes it very suitable for traveling, camping and events.