How Long Do Biodegradable Urns Last?

If you are choosing a biodegradable urn, one of the first questions is how long it lasts, both while you keep it and once it is buried or placed in water. The answer depends on the material and the conditions. This guide explains what to expect.

Quick answer: A biodegradable urn lasts indefinitely while kept dry indoors. Once it meets moisture, the timing varies by type: water-burial urns made from paper, sand or minerals disperse within a few minutes, dense salt urns take up to about four hours, and land-burial urns break down in the soil over several weeks to months, depending on rainfall. Kept dry at home beforehand, the urn stays solid and intact for as long as you need.

Why do some urns break down faster than others?

Two things decide how long a biodegradable urn lasts: the material it is made from, and the environment it ends up in. Kept dry at home, every biodegradable urn stays solid and stable. It is moisture that begins the process, so a water burial works much faster than a land burial, and a dense material lasts longer than a light one.

Water-burial urns: minutes to hours

Water-burial urns are designed to disperse fairly quickly once placed on the water.

• Paper and plant-fibre urns such as the Journey Urn, made from mulberry bark, float for a few minutes then submerge and release the ashes gently.
• Sand and mineral urns such as the Oceane Quartz Urn are bound with natural adhesives that dissolve on contact with water, dispersing over a few minutes.
• Shell-shaped urns like the Shell Water Urn float briefly before sinking and breaking down.
• Salt urns such as the Himalayan Rock Salt Urn are dense and heavy, so they sink quickly and then dissolve over up to about four hours, depending on the water and weather.

Land-burial urns: weeks to months

Buried in soil, a biodegradable urn breaks down much more slowly because moisture reaches it gradually. Most disperse over several weeks to a few months as the earth naturally melds with the urn, though heavy rainfall speeds this up and dry ground slows it down. Plant-based and earth urns such as the Simplicity Earthurn are made for exactly this, returning the ashes gently to the ground. You can see the full range in our biodegradable urns collection.

How long does it last before you use it?

Indefinitely, as long as it is kept dry. Biodegradable urns only begin to break down when they meet moisture, so you can keep one at home for as long as you need before deciding on a burial or water ceremony. There is no rush, and no legal time limit on keeping ashes at home.

For the practical side, see our guides on how cremation urns are buried and how to scatter ashes.

Frequently asked questions

How long does a biodegradable urn take to dissolve in water?

Most water-burial urns made from paper, sand or minerals disperse within a few minutes. Dense salt urns sink quickly and then dissolve over up to about four hours, depending on the movement of the water and the weather.

How long does a biodegradable urn take to break down in soil?

Buried in the ground, most biodegradable urns break down over several weeks to a few months, returning the ashes to the soil. Rainfall and ground conditions affect the exact timing.

How long can I keep a biodegradable urn before using it?

Indefinitely, as long as it stays dry. Biodegradable urns only start to break down when they meet moisture, so you can keep one safely at home for as long as you need.

Can the same urn be used for water or land burial?

Some can, and they react to the conditions, breaking down quickly in water or slowly in soil. Each product page states whether an urn is for water, land, or both.