## Common ground
All options describe water cisterns made from different solid materials, used for storing water.
## Options at a glance
**3922.90 – Plastic**
- **Defining trait:** Made from synthetic polymer (plastic), lightweight and corrosion-resistant.
- **Typical examples:** Household rainwater tanks, portable storage bins.
- **Best fit when:** Lightweight, low-cost, or outdoor use with minimal structural load.
**4016.99 – Rubber**
- **Defining trait:** Flexible, elastic material; typically used in inflatable or collapsible forms.
- **Typical examples:** Inflatable water bladders, temporary storage bags.
- **Best fit when:** Portable, temporary, or space-saving needs.
**6803.00 – Slate**
- **Defining trait:** Natural stone, hard and durable but heavy and brittle.
- **Typical examples:** Decorative or architectural water reservoirs in historic buildings.
- **Best fit when:** Aesthetic or permanent installation where weight isn’t an issue.
**6810.99 – Cement concrete or artificial stone**
- **Defining trait:** Rigid, heavy, and long-lasting; often cast in place.
- **Typical examples:** Underground water tanks, large-scale reservoirs.
- **Best fit when:** Permanent, high-capacity, or buried installations.
**6811.89 – Asbestos cement or cellulose fiber cement**
- **Defining trait:** Composite material with fibrous reinforcement; now largely phased out due to health risks.
- **Typical examples:** Older industrial or rural water tanks.
- **Best fit when:** Identifying legacy infrastructure (not recommended for new use).
**6910 – Ceramic**
- **Defining trait:** Fired clay, non-porous and heat-resistant but fragile.
- **Typical examples:** Traditional storage jars, decorative fountains.
- **Best fit when:** Small-scale, indoor, or decorative use.
**6911.90 – Porcelain or china**
- **Defining trait:** High-fired, glazed ceramic; very smooth and non-reactive.
- **Typical examples:** Laboratory or medical water storage vessels.
- **Best fit when:** Hygienic, high-purity, or precision applications.
**7017 – Glass**
- **Defining trait:** Transparent, chemically inert, but fragile and heavy.
- **Typical examples:** Display tanks, lab equipment, aquariums.
- **Best fit when:** Visibility of water level or chemical purity required.
**7324.90 – Iron or steel**
- **Defining trait:** Strong, durable, but prone to rust without coating.
- **Typical examples:** Industrial water reservoirs, large above-ground tanks.
- **Best fit when:** High strength and capacity needed, with corrosion protection.
**7418.20 – Copper**
- **Defining trait:** Naturally antimicrobial, conducts heat, expensive.
- **Typical examples:** High-end residential or historical water storage.
- **Best fit when:** Antimicrobial properties or aesthetic value are key.
**7615.20 – Aluminium**
- **Defining trait:** Lightweight, corrosion-resistant, recyclable.
- **Typical examples:** Mobile water tanks, rooftop installations.
- **Best fit when:** Portability and durability in harsh environments.
**7907.00 – Zinc**
- **Defining trait:** Coated or galvanized; used for protection but not common for cisterns.
- **Typical examples:** Rare; mostly in roofing or protective coatings.
- **Best fit when:** Not typical for standalone cisterns; likely a misclassification.
## Key differences
| Material | Weight | Durability | Corrosion Resistance | Common Use Case |
|--------|--------|------------|----------------------|----------------|
| Plastic | Low | Medium | High | Portable, household |
| Rubber | Very low | Low | High (inflatable) | Temporary, collapsible |
| Slate | High | High | High | Decorative, permanent |
| Concrete | High | Very high | Medium | Buried, large-scale |
| Asbestos cement | Medium | High | Medium | Legacy systems |
| Ceramic | Medium | Low | High | Small, indoor |
| Porcelain | Medium | Low | High | Hygienic, lab |
| Glass | High | Low | High | Transparent, display |
| Iron/Steel | High | High | Low (unless coated) | Industrial |
| Copper | Medium | Medium | High | Antimicrobial, aesthetic |
| Aluminium | Low | High | Very high | Mobile, outdoor |
| Zinc | Medium | Medium | Medium | Coatings, not cisterns |
## How to choose
- Is the cistern lightweight and portable? → 3922.90 or 7615.20
- Is it inflatable or collapsible? → 4016.99
- Is it buried or permanent? → 6810.99 or 7324.90
- Does it need to be transparent? → 7017
- Is it for high hygiene or lab use? → 6911.90
- Is it decorative or historical? → 6803.00 or 6910
## Overlaps & pitfalls
- Plastic (3922.90) and aluminum (7615.20) both offer lightweight, corrosion-resistant options—choose based on cost vs. strength.
- Asbestos cement (6811.89) is obsolete; avoid unless identifying old infrastructure.
- Zinc (7907.00) is not standard for cisterns—likely a misclassification.
- No option clearly prioritizes function over material; use the **main purpose** (e.g., storage, hygiene, portability) to decide